CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM
erature is much higher indicated by
Temperature is much higher indicated by
Rotating speed of idle speed is lower
Much higher voltage of upstream oxygen
conditioner compressor relay control
4.1 ENGINE DTC (DIAGNOSTIC TROUBLE CODE) LIST
DTC Definition DTC Definition
P0107
P0108
P0112
P0113
P0117
Much lower voltage of the air intake
pressure sensor
Much higher voltage of the air intake
pressure sensor
Indicated temperature is much lower of
the air intake temperature sensor
Temp
the air intake temperature sensor
Temperature is much lower indicated by
engine coolant temperature sensor
P0340 Phase sensor signal failure
P0342
P0343
P0443
Much lower voltage of the phase
sensor
Much higher voltage of the phase
sensor
Canister control valve drive grade
control circuit failure
Much lower voltage of canister
P0444
control valve drive grade control
circuit
Much higher voltage of canister
P0118
P0122
P0123
P0130
P0132
engine coolant temperature sensor
The circuit voltage of throttle position
sensor is much lower
The circuit voltage of throttle position
sensor is much higher
Unreasonable failure of the upstream
oxygen sensor signal
sensor
P0134 Signal failure of upstream oxygen sensor P0508
P0135
P0171
P0172
Heating circuit failure of upstream
oxygen sensor
Closed loop air fuel ratio control self
adapting exceeds it maximum limit
Closed loop air fuel ratio control self
adapting exceeds it minimum limit
P0445
control valve drive grade control
circuit
P0480
Air conditioner condenser cooling
fan relay control circuit failure
P0500 Unreasonable failure of speed signal
P0506
P0507
than target idle speed
Rotating speed of idle speed is
higher than target idle speed
Idle speed regulator control circuit
voltage is too low
P0509
P0511
Idle speed regulator control circuit
voltage is too high
Idle speed regulator control circuit
failure
P0560 System voltage signal unreasonable
P0201 The 1st cylinder injector circuit failure P0562 System voltage is too low
P0202 The 2nd cylinder injector circuit failure P0563 System voltage is too high
P0203 The 3rd cylinder injector circuit failure P0601 ECU testing code failure
P0204 The 4th cylinder injector circuit failure P0602 ECU diagnosis data ID code failure
P0230 Fuel pump control circuit failure P0645
Air conditioner compressor relay
control circuit failure
Much lower voltage of air
P0325 Knock sensor circuit failure P0646
circuit
32
CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM
conditioner compressor relay control
put the
if it is
check the voltage between pin No. 3 and pin No. 1 by
Check if it is short circuit to ground between ECU pin
Check if it is open circuit or short circuit to power supply
Much higher voltage of air
P0335 Crank shaft position sensor signal failure P0647
circuit
P0336
Crank shaft position sensor signal
unreasonable failure
P1651 Trouble light control circuit failure
4.2 DIAGNOSIS FLOW WHEN THERE IS DIFFERENT DTC
P0107 Much lower voltage of the air intake pressure sensor
No. Operating steps Result Follow up steps
Connect the diagnostic tester and commutator,
1
ignition switch to “ON”
Observe “air intake pressure” item in data flow,
2
about 101kpa (specific data is correlated to that time
air pressure).
Take off the joint of cable air intake pressure sensor,
Yes To step No. 5
No Next steps
Yes To step No. 5
Next step
3
multimeter and look if it is around 5V.
4
No. 17, No. 33, No. 37 and sensor connector No.1,
No.3 and No. 4.
No Next step
Yes
Repair or replace
cable
No Next step
Start the engine at idle speed. Step on the accelerator
slowly approach to open completely and observe the
5
value changes of diagnostic tester “air intake
pressure”, the changes should be not big; step on the
accelerator quickly to complete open, the displayed
Yes Diagnosis help
No Replace the sensor
value should be reach up to 90kpa instantaneous.
DTC: P0108 Much higher voltage of the air intake pressure sensor
No. Operating steps Result Follow up steps
1
2
3
4
Connect the diagnostic tester and commutator, put the
ignition switch to “ON”
Observe “air intake pressure” item in data flow, if it is
about 101kpa(specific data is correlated to that time air
pressure)
Take off the joint of cable air intake pressure sensor,
check the voltage between pin No. 3 and pin No. 1 by
multimeter and look if it is around 5V.
between ECU pin No. 17, No. 33, No. 37 and sensor
connector No.1, No.3 and No. 4.
Next step
Yes To step No. 5
No Next steps
Yes To step No. 5
No Next step
Yes
Repair or replace
cable
No Next step
Yes Diagnosis help5 Start the engine at idle speed. Step on the accelerator
slowly approach to open completely and observe the
No Replace the
33
CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM
value changes of diagnostic tester “air intake pressure”,
the changes should be not big; step on the accelerator
quickly to complete open, the displayed value should be
reach up to 90kpa instantaneous.
sensor
34
CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM
if it is
Check if it is open circuit or short circuit to power supply
if it is
★ there is perhaps open
DTC P0112 Circuit voltage is much lower of the throttle position sensor
No. Operating steps Result Follow up steps
1
Connect the diagnostic tester and commutator, put the
ignition switch to “ON”
Observe “air intake temperature” item in data flow,
same temperature with air intake pipe(specific data is
2
correlated to the engine temperature at that time)
Notice: if the value is - 40★ there is perhaps open circuit
failure in the circuit.
Take off the joint of cable air intake temperature sensor,
check the resistance values using multimeter between
3
sensor connector No. 1 and No. 2 and check if it is
corresponding to its temperature (please reference the
related section of this service manual)
Take off the joint of cable air intake temperature sensor,
4
check the voltage between pin No.1 and pin No.2 by
multimeter and look if it is around 5V.
5
between ECU pin No. 17, No. 40 and sensor connector
No.1, No.2
Next step
Yes To step No. 5
No Next step
Yes Next step
No Replace sensor
Yes To step 5
No Next step
Repair or
Yes
replace
cable
No Next step
Start the engine at idle speed. Observe the value changes
6
of diagnostic tester “air intake temperature”, the value
should increase with the increase of the engine intake air.
Yes Diagnosis help
No
Replace the
sensor
DTC: P0113 Temperature is much higher indicated by the air intake temperature sensor
No. Operating steps Result Follow up steps
1
Connect the diagnostic tester and commutator, put the
ignition switch to “ON”.
Observe “air intake temperature” item in data flow,
Next step
Yes To step No. 5
same temperature with air intake pipe(specific data is
2
correlated to the engine temperature at that time)
Notice: if the value always is - 40
No Next step
circuit failure in the circuit.
Take off the joint of cable air intake temperature sensor,
Yes Next step
check the resistance values using multimeter between
3
sensor connector No. 1 and No. 2 and check if it is
corresponding to its temperature (please reference the
No Replace sensor
related section of this service manual).
Take off the joint of cable air intake temperature sensor,
4
check the voltage between pin No.1 and pin No.2 by
multimeter and look if it is around 5V.
Yes To step 5
No Next step
35
CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM
Repair or
5
Check if it is short circuit to ground between ECU pin
No. 17, No. 40 and sensor connector No.1, No.2
Yes
replace
cable
No Next step
Start the engine at idle speed. Observe the value changes
6
of diagnostic tester “air intake temperature”, the value
should increase with the increase of the engine intake air.
Yes Diagnosis help
No
Replace the
sensor
DTC: P0117 Temperature is much lower indicated by engine coolant temperature sensor.
No. Operating steps Result Follow up steps
1
Connect the diagnostic tester and commutator, put
the ignition switch to “ON”.
Observe “coolant temperature” item in data flow, if
Yes To step 6
Next step
it is same temperature with engine temperature
(specific data is correlated to the engine temperature
2
at that time).
No Next
Notice: if the value always is - 40★ there is perhaps
open circuit failure in the circuit.
Take off the joint of coolant temperature sensor on
Yes Next step
the cable, check the resistance values using
multimeter between sensor connector No. 1 and No.
3
2 and check if it is corresponding to its temperature
No Replace sensor
(please reference the related section of this service
manual).
Take off the joint of coolant temperature sensor on
4
the cable, check the voltage between pin No.1 and
pin No.2 by multimeter and observe if it is around
Yes To step 6
No Next step
5V.
Check if it is open circuit or short circuit to power
5
supply between ECU pin No.39, No. 35 and sensor
connector No.1, No.2.
Start the engine at idle speed. Observe the value
changes of diagnostic tester “coolant temperature”,
6
the value should increase with the increase of the
Yes
No Next step
Yes Diagnosis help
No Replace sensor
Repair or replace
cable
engine coolant temperature.
DTC: P0118 Temperature is much higher indicated by engine coolant temperature sensor
No. Operating steps Result Follow up steps
1
2
Connect the diagnostic tester and commutator, put
the ignition switch to “ON”.
Observe “coolant temperature” item in data flow, if
it is same temperature with engine temperature
(specific data is correlated to the engine temperature
36
Next step
Yes To step 6
No Next
CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM
at that time).
Notice: if the value always is - 40★ there is perhaps
open circuit failure in the circuit.
Take off the joint of coolant temperature sensor on
Yes Next step
the cable, check the resistance values using
multimeter between the sensor connector No. 1 and
3
the No. 2 and check if it is corresponding to its
No Replace sensor
temperature (please reference the related section of
this service manual).
Take off the joint of coolant temperature sensor on
4
the cable, check the voltage between pin No.1 and
pin No.2 by multimeter and observe if it is around
Yes To step 6
No Next step
5V.
5
Check if it is short circuit to ground between ECU
pin No.39, No. 35 and sensor connector No.1, No.2.
Yes
Repair or replace
No Next step
cable
Start the engine at idle speed. Observe the value
changes of diagnostic tester “coolant temperature”,
6
the value should increase with the increase of the
Yes Diagnosis help
No Replace sensor
engine coolant temperature.
DTC: P0122 Indicated temperature is much lower of the air intake temperature sensor.
No. Operating steps Result Follow up steps
1
2
Connect the diagnostic tester and commutator, put
the ignition switch to “ON”.
Observe “throttle valve absolute opening” item in
data flow, check the value if it is between 4% and
10% (specific data is correlated to the vehicle type).
Step on the accelerator slowly to complete opening
Next step
Yes Next step
No To step No. 5
Yes Next step
and observe “throttle valve absolute opening” item
3
in data flow, check if the value is increased to around
85-90% with the opening of the throttle valve
No To step No. 5
(specific data is correlated to the vehicle type).
Repeat step 3 and observe “throttle valve absolute
4
opening” item in data flow, and check if there is
jump during the changes.
Take off the joint of throttle valve positioning sensor
on the cable, check if there is short circuit to ground
5
Yes Replace the sensor
No Next step
Yes
Repair or replace
cable
between pin No.17, No.32, No.16 of ECU and pin
No.1, No.2, No.3.
No Next step
Check the voltage between pin No.1 and pin No.2 by
6
multimeter and observe if it is around 5V.
37
Yes Replace sensor
No Diagnosis help
CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM
DTC: P0123 Circuit voltage is much higher of the throttle position sensor
No. Operating steps Result Follow up steps
1
2
Connect the diagnostic tester and commutator, put
the ignition switch to “ON”
Observe “throttle valve absolute opening” item in
data flow, check the value if it is between 4% and
10% (specific data is correlated to the vehicle type).
Step on the accelerator slowly to complete opening
Next step
Yes Next step
No To step No. 5
Yes Next step
and observe “throttle valve absolute opening” item
3
in data flow, check if the value is increased to around
85-90% with the opening of the throttle valve
No To step No. 5
(specific data is correlated to the vehicle type).
Repeat step 3 and observe “throttle valve absolute
4
opening” item in data flow, and check if there is
jump during the changes.
Take off the joint of throttle valve positioning sensor
5
on the cable, check if there is open circuit or short
Yes Replace the sensor
No Next step
Yes
Repair or replace
cable
circuit to power supply between pin No.17, No.32,
No.16 of ECU and pin No.1, No.2, No.3 of sensor
No Next step
Check the voltage between pin No.1 and pin No.2 by
6
multimeter and observe if it is around 5V.
Yes Replace sensor
No Diagnosis help
DTC: P0130 Unreasonable failure of the upstream oxygen sensor signal
(Notice: below diagnosis process is fit for those without P0135 at the same time; if there is
P0135 failure, please deal with P0135 failure at first and then check as below.)
No. Operating steps Result Follow up steps
1
Connect the diagnostic tester and commutator, put
the ignition switch to “ON”
Start the engine and leave it at idle speed until its
Yes Diagnosis help
Next step
coolant reaches to the normal value. Observe the
2
value changes of “oxygen sensor voltage” item on
diagnostic meter, the displayed value should change
No Next step
rapidly from 100mV-900mV.
Check if there is short circuit to ground between pin
No.36, No.18, of ECU and pin A (opposite to oxygen
3
sensor gray connecting line), B (opposite to oxygen
sensor black connecting line).
Yes
No Next step
Repair or change
cable
DTC: P0132 Much higher voltage of upstream oxygen sensor
(Notice: below diagnosis process is fit for those without P0135 at the same time; if there is
P0135 failure, please deal with P0135 failure at first and then check as below.)
38
CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM
No. Operating steps Result Follow up steps
Connect the diagnostic tester and commutator, put the
1
ignition switch to “ON”.
Start the engine and leave it at idle speed until its
Yes Diagnosis help
Next step
coolant reaches to the normal value. Observe the value
2
changes of “oxygen sensor voltage” item on diagnostic
meter, the displayed value should change rapidly from
No Next step
100mV-900mV.
Check if there is short circuit to power supply between
3
pin No.36, No.18, of ECU and pin A(opposite to
Yes
Repair or change
cable
oxygen sensor gray connecting line), B (opposite to
oxygen sensor black connecting line).
A, check if the exhaust system is jammed
4
B, check if the injector is leaking
C, check if the fuel pressure is over higher
D, check if the valve clearance is over smaller etc.
No Diagnosis help
Check and repair
Yes
according to
diagnosis
No Diagnosis help
DTC: P0134 Signal failure of upstream oxygen sensor
(Notice: below diagnosis process is fit for those without P0135 at the same time; if there is
P0135 failure, please deal with P0135 failure at first and then check as below.)
No. Operating steps Result Follow up steps
Connect the diagnostic tester and commutator, put the
1
ignition switch to “ON”.
Start the engine and leave it at idle speed until its
Yes Diagnosis help
Next step
coolant temperature reaches to the normal value.
2
Observe the value changes of “oxygen sensor voltage”
item on diagnostic meter, the displayed value should
No Next step
change rapidly from 100mV-900mV.
Check if there is open circuit between pin No.36,
No.18, of ECU and pin A (opposite to oxygen sensor
3
Yes
Repair or change
cable
gray connecting line), B (opposite to oxygen sensor
black connecting line) of sensor joint.
No Diagnosis help
DTC: P0135 Heating circuit failure of upstream oxygen sensor
No. Operating steps Result Follow up steps
Connect the diagnostic tester and commutator, put the
1
ignition switch to “ON”.
Take off the oxygen sensor joint on the cable and
Yes Next step
Next step
check the voltage between the pins of C (opposite to
2
oxygen sensor white connecting line) and D (opposite
to oxygen sensor white connecting line) by multimeter,
No To step No.4
and observe if it is about 12V.
3 Check the resistance value between oxygen sensor Yes Next step
39
CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM
connectors C (white) and D (white) using multimeter,
and observe if it is 2-5Ω when it is 20★.
Check the fuse inside of oxygen sensor heating circuit
4
and observe if it is blow.
Check if there is open circuit or short circuit to power
supply between ECU pin No.1, main relay sensor
5
No.87 and pin C (opposite to oxygen sensor white
connecting line), D (opposite to oxygen sensor white
No Change sensor
Yes Change fuse
Next step
Yes
Repair or change
cable
No Diagnosis help
connecting line) of sensor joint.
DTC: P0171 Closed loop air fuel ratio control self adapting exceeds it maximum limit
(Notice: below diagnosis flow is fit for when air intake pressure sensor failure, canister
control valve failure and oxygen sensor failure are not appeared at the same time; if there are
failures existing at the same time please deal with other failures at first and then do as below.)
No. Operating steps Result Follow up steps
1
Connect the diagnostic tester and commutator, put the
ignition switch to “ON”.
Start the engine and leave it at idle speed until its
Next step
Yes Next step
coolant temperature reaches to the normal value.
2
Observe the value changes of “oxygen sensor voltage”
item on diagnostic meter, and the displayed value keeps
No Diagnosis help
around the value of 100mV at some working conditions.
Connect the fuel pressure meter (connection position is
the front end of fuel distributing pipe assembly fuel
intake pipe); start the engine and check the fuel pressure
3
Yes
Repair or replace
the cable
at idle speed conditions if it is around 260kpa; take off
the vacuum pipe on fuel pressure regulator, check the
No Next step
pressure and observe if it is around 300kpa.
Check if there is short circuit to ground between ECU
pin No.36, No.18 and pin A(opposite to oxygen sensor
4
Yes
Repair or replace
cable
gray connecting line), pin B (opposite to oxygen sensor
black connecting line) of sensor joint.
A, check if there is a heavy leaking in air intake system
B, check if the injector is jammed
5
C, check if the clearance of spark plug is too big
D, check if the sub live wire resistance is too big
No Next step
Yes
Repair according
to diagnosis data
No Diagnosis help
E, check if the valve clearance is too big etc.
40
CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM
DTC: P0172 Closed loop air fuel ratio control self adapting exceeds it minimum limit
(Notice: below diagnosis flow is fit for when air intake pressure sensor failure, canister
control valve failure and oxygen sensor failure are not appeared at the same time; if there are
failures existing at the same time please deal with other failures at first and then do as below.)
No. Operating steps Result Follow up steps
Connect the diagnostic tester and commutator, put the
1
ignition switch to “ON”
Start the engine and leave it at idle speed until its
Yes Next step
Next step
coolant temperature reaches to the normal value.
Observe the value changes of “oxygen sensor voltage”
2
item on diagnostic meter, and the displayed value
No Diagnosis help
keeps around the value of 900mV at some working
conditions.
Connect the fuel pressure meter (connection position is
the front end of fuel distributing pipe assembly fuel
3
intake pipe); start the engine and check the fuel
pressure at idle speed conditions if it is around 260kpa;
take off the vacuum pipe on fuel pressure regulator,
Yes
No
Repair or replace
the cable
Check and repair
fuel system
check the pressure and observe if it is around 300kpa.
Check if there is short circuit to power supply between
ECU pin No.36, No.18 and pin A (opposite to oxygen
4
Yes
Repair or replace
cable
sensor gray connecting line), pin B (opposite to
oxygen sensor black connecting line) of sensor joint.
A, check if the injector is leaking
5
B, check if the exhaust pipe is jammed
C, check if the valve clearance is too small etc.
No Next step
Yes
Repair according
to diagnosis data
No Diagnosis help
DTC: P0201 The 1stcylinder injector circuit failure
No. Operating steps Result Follow up steps
Connect the diagnostic tester and commutator, put the
1
ignition switch to “ON”
Take off the 1stcylinder injector joint from the cable,
2
check the voltage value between this joint pin No.1
and the power cathode by multimeter and observe if it
Yes To step No.4
No Next step
Next step
is 12V.
Check if there is open circuit or short circuit to ground
3
between the 1stinjector joint pin No.1 and main relay.
Yes
Repair or replace
the cable
No Next step
st
Check the resistance value by multimeter between 1
cylinder injector pin No.1 and No.2, and observe if it
4
Yes Next step
No Change injector
is 11-13Ω when it is 20℃.
5 Check the voltage value by multimeter between 1
41
st
Yes Repair according to
CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM
diagnosis datacylinder injector pin No.2 and power supply cathode,
and observe if it is around 3.7V.
Check if there is open circuit or short circuit to ground
6
between 1stcylinder injector joint pin No.2 and the
ECU pin No.27.
No Diagnosis help
Yes
Repair or replace
cable
No Diagnosis help
DTC: P0202 The 2ndcylinder injector circuit failure
No. Operating steps Result Follow up steps
Connect the diagnostic tester and commutator, put the
1
ignition switch to “ON”
Take off the 2ndcylinder injector joint from the cable,
2
check the voltage value between this joint pin No.1
and the power cathode by multimeter and observe if it
Yes To step No.4
No Next step
Next step
is 12V.
Check if there is open circuit or short circuit to ground
3
between the 2ndinjector joint pin No.1 and main relay.
Yes
Repair or replace
the cable
No Next step
nd
Check the resistance value by multimeter between 2
cylinder injector pin No.1 and No.2, and observe if it
4
Yes Next
No Change injector
is 11-13Ω when it is 20℃.
Check the voltage value by multimeter between 2
5
cylinder injector pin No.2 and power supply cathode,
and observe if it is around 3.7V.
Check if there is open circuit or short circuit to ground
6
between 2ndcylinder injector joint pin No.2 and the
ECU pin No.6.
nd
Yes Diagnosis help
No Next step
Yes
Repair or replace
cable
No Diagnosis help
DTC: P0203 The 3rdcylinder injector circuit failure
No. Operating steps Result Follow up steps
Connect the diagnostic tester and commutator, put the
1
ignition switch to “ON”
Take off the 3rdcylinder injector joint from the cable,
2
check the voltage value between this joint pin No.1
and the power cathode by multimeter and observe if it
Yes To step No.4
No Next step
Next step
is 12V.
Check if there is open circuit or short circuit to ground
between the 3rdinjector joint pin No.1 and main relay.
Yes
Repair or replace
the cable3
No Next step
rd
Check the resistance value by multimeter between 3
cylinder injector pin No.1 and No.2, and observe if it
4
Yes Next step
No Change injector
is 11-13Ω when it is 20℃.
5 Check the voltage value by multimeter between 3
42
rd
Yes Diagnosis help
CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM
cylinder injector pin No.2 and power supply cathode,
and observe if it is around 3.7V.
Check if there is open circuit or short circuit to ground
6
between 3rdcylinder injector joint pin No.2 and the
ECU pin No.7.
No Next step
Yes
Repair or replace
cable
No Diagnosis help
DTC: P0204 The 4thcylinder injector circuit failure
No. Operating steps Result Follow up steps
Connect the diagnostic tester and commutator, put the
1
ignition switch to “ON”
Take off the 4thcylinder injector joint from the cable,
2
check the voltage value between this joint pin No.1
and the power cathode by multimeter and observe if it
Yes To step No.4
No Next step
Next step
is 12V.
Check if there is open circuit or short circuit to ground
3
between the 4thinjector joint pin No.1 and main relay.
Yes
Repair or replace
the cable
No Next step
th
Check the resistance value by multimeter between 4
cylinder injector pin No.1 and No.2, and observe if it
4
Yes Next step
No Replace injector
is 11-13Ω when it is 20℃.
Check the voltage value by multimeter between 4
5
cylinder injector pin No.2 and power supply cathode,
and observe if it is around 3.7V.
Check if there is open circuit or short circuit to ground
6
between 4thcylinder injector joint pin No.2 and the
ECU pin No.47.
th
Yes Diagnosis help
No Next step
Yes
Repair or replace
cable
No Diagnosis help
DTC: P0230 Fuel pump control circuit failure
No. Operating steps Result Follow up steps
Connect the diagnostic tester and commutator, put the
1
ignition switch to “OFF”
Take off the fuel pump relay and put ignition switch to
Yes To step No.4
Next step
“ON”; check the voltage separately between fuel
2
pump relay power supply ends - that is relay pin No.
30 and No.86 and power supply cathode, and observe
No Next step
if it is around 12V.
Check if there is open circuit or short circuit to ground
of the relay power supply ends circuit.
Yes
Repair or replace
the cable3
No To step No.2
Check the voltage by multimeter between fuel pump
relay control ends that is relay pin No. 85 and power
supply cathode and observe if it is around 3.7V.
5 Check if there is open circuit or short circuit to ground
Yes
No Next step
Yes Repair or replace
Replace fuel
pump relay4
43
CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM
cableor to power supply between relay control ends that is
relay pin No.85 and ECU pin No.69.
No Diagnosis help
DTC: P0325 Knock sensor circuit failure
No. Operating steps Result Follow up steps
Connect the diagnostic tester and commutator, put the
1
ignition switch to “OFF”
Take off the knock sensor joint from the cable; check
2
the resistance value by multimeter between knock
sensor connector No.1and No.2 and observe if it is
Yes Next step
No Change sensor
Next step
1MΩ.
Check if there is open circuit or short circuit to ground
3
or to power supply between circuit of knock sensor
joint No.1, No.2 and ECU pin No.19, No. 20
Replace the knock sensor according to the regulation;
4
try running the vehicle and make the engine speed
exceed 2200rpm. Check if the DTC P0325 will appear
again.
Yes
No To step No.2
Yes Diagnosis help
No
Repair or replace
the cable
Check if it is a
occasional fault
DTC: P0335 Crank shaft position sensor signal failure
No. Operating steps Result Follow up steps
Connect the diagnostic tester and commutator, put the
1
Take off the speed sensor joint from the cable; check
ignition switch to “OFF”
Yes Next step
Next step
the resistance value by multimeter between speed
2
sensor connector No.2and No.3 and observe if it is
No Replace sensor
around 770-950MΩwhen it is 20℃
Check if there is open circuit or short circuit to ground
3
or to power supply between circuit of speed sensor
joint No.2, No.3 and ECU pin No.34, No. 15
4
Check the flywheel signal disc if it is in good
conditions.
Yes
No Next step
Yes Diagnosis help
No
Repair or replace
the cable
Replace signal
disc
DTC: P0336 Crank shaft position sensor signal unreasonable failure
No. Operating steps Result Follow up steps
1
Connect the diagnostic tester and commutator, put
the ignition switch to “OFF”
Take off the speed sensor joint from the cable; check
Yes Next step
Next step
the resistance value by multimeter between speed
2
sensor connector No.2and No.3 and observe if it is
No Replace sensor
around 770-950MΩwhen it is 20℃
44
CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM
Check if there is open circuit or short circuit to
ground or to power supply between circuit of speed
3
sensor joint pin No.2, No.3 and ECU pin No.34, No.
15
4
Check the flywheel signal disc if it is in good
conditions.
Yes
Repair or replace the
cable
No Next step
Yes Diagnosis help
No Replace signal disc
45
CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM
DTC: P0340 Phase sensor signal failure
No. Operating steps Result Follow up steps
1
2
3
Connect the diagnostic tester and commutator, put the
ignition switch to “ON”
Take off the phase sensor joint from the cable; check the
voltage value by multimeter between phase sensor joint pin
No.3 and No.1; and observe if it is around 12V.
Check if there is open circuit or short circuit to ground
between circuit of phase sensor joint pin No.3 and main
relay pin No.87; check if there is bad contact of phase
sensor connector No.1.
Next step
Yes To step No.4
No Next step
Repair or
Yes
replace the
cable
No Next step
Check the voltage if it is around 9.9V between phase sensor
4
joint pin No.2 and power supply cathode.
Check if there is open circuit or short circuit to power
5
supply or to ground between phase sensor joint pin No.2
and ECU pin No.79.
Yes To step 6
No Next step
Yes
Repair or
replace cable
No Next step
Yes Diagnosis help
6 Check the camshaft signal disc if it is in good conditions.
No
Replace signal
disc
DTC: P0342 Much lower voltage of the phase sensor
No. Operating steps Result Follow up steps
1
Connect the diagnostic tester and commutator, put the
ignition switch to “ON”
Take off the phase sensor joint from the cable; check the
2
voltage value by multimeter between phase sensor joint pin
No.3 and No.1; and observe if it is around 12V.
Check if there is open circuit or short circuit to ground
3
between circuit of phase sensor joint pin No.3 and main
relay pin No.87; check if there is bad contact of phase
sensor connector No.1.
Yes To step No.4
No Next step
Yes
No Next step
Next step
Repair or
replace the
cable
Check the voltage if it is around 9.9V between phase sensor
4
joint pin No.2 and power supply cathode.
Check if there is open circuit or short circuit to power
5
supply or to ground between the circuit of phase sensor
joint pin No.2 and ECU pin No.79.
6 Check the camshaft signal disc if it is in good conditions.
46
Yes To step 6
No Next step
Yes
Repair or
replace cable
No Next step
Yes Diagnosis help
No
Replace signal
disc
CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM
DTC: P0343 Much higher voltage of the phase sensor
No. Operating steps Result Follow up steps
Connect the diagnostic tester and commutator, put the
1
ignition switch to “ON”
Take off the phase sensor joint from the cable; check
the voltage value by multimeter between phase sensor
2
joint pin No.3 and No.1; and observe if it is around
Yes To step No.4
No Next step
Next step
12V.
Check if there is open circuit or short circuit to ground
between circuit of phase sensor joint pin No.3 and main
3
Yes
Repair or replace
the cable
relay pin No.87; check if there is bad contact of phase
sensor connector No.1.
4
Check the voltage if it is around 9.9V between phase
sensor joint pin No.2 and power supply cathode.
No Next step
Yes To step 6
No Next step
Check if there is open circuit or short circuit to power
5
supply or to ground between the circuit of phase sensor
joint pin No.2 and ECU pin No.79.
6
Check the camshaft signal disc if it is in good
conditions.
Yes
No Next step
Yes Diagnosis help
No
Repair or replace
cable
Replace signal
disc
DTC: P0443 Canister control valve drive grade control circuit failure
No. Operating steps Result Follow up steps
Connect the diagnostic tester and commutator, put the
1
ignition switch to “ON”
Take off the canister control valve joint from the cable;
2
check the voltage value by multimeter between this
joint pin No.1 and power supply cathode; and observe
Yes To step No.4
No Next step
Next step
if it is around 12V.
Check if there is open circuit or short circuit to ground
3
of the canister control valve power supply ends circuit.
Yes
Repair or replace
the cable
No To step No.2
Check the resistance value if it is around 22-30Ωwhen
Yes Next step
4
it is 20℃ between canister control valve pin No.1 and
pin No.2.
Check the voltage if it is around 3.7V between canister
5
control valve joint pin No.1 and power supply cathode.
6
Check if there is open circuit between the circuit of
canister joint pin No.2 and ECU pin No. 46.
47
No Replace the valve
Yes Diagnosis help
No Next step
Yes
Repair or replace
cable
No Diagnosis help
CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM
DTC: P0444 Much lower voltage of canister control valve drive grade control circuit
No. Operating steps Result Follow up steps
Connect the diagnostic tester and commutator, put the
1
ignition switch to “ON”
Take off the canister control valve joint from the cable;
2
check the voltage value by multimeter between this
joint pin No.1 and power supply cathode; and observe
Yes To step No.4
No Next step
Next step
if it is around 12V.
Repair or
Check if there is open circuit or short circuit to ground
3
of the canister control valve power supply ends circuit.
Yes
replace the
cable
No To step No.2
Check the resistance value if it is around 22-30Ω when
Yes Next step
4
it is 20℃ between canister control valve pin No.1 and
pin No.2.
Check the voltage by the multimeter if it is around
5
3.7V between canister control valve joint pin No.1 and
power supply cathode.
6
Check if there is short circuit to ground between the
circuit of canister joint pin No.2 and ECU pin No. 46.
No
Yes Diagnosis help
No Next step
Yes
Replace the
valve
Repair or
replace cable
No Diagnosis help
DTC: P0445 Much higher voltage of canister control valve drives grade control circuit
No. Operating steps Result Follow up steps
1
2
Connect the diagnostic tester and commutator, put the
ignition switch to “ON”
Take off the canister control valve joint from the cable;
check the voltage value by multimeter between this joint
pin No.1 and power supply cathode; and observe if it is
Next step
Yes To step No.4
No Next step
around 12V.
Check if there is open circuit or short circuit to ground of
3
the canister control valve power supply ends circuit.
Yes
Repair or replace
the cable
No To step No.2
Check the resistance value if it is around 22-30Ωwhen it
Yes Next step
4
is 20℃ between canister control valve pin No.1 and pin
No.2.
Check the voltage by the multimeter if it is around 3.7V
5
between canister control valve joint pin No.1 and power
supply cathode.
6
Check if there is short circuit to power supply between
the circuit of canister joint pin No.2 and ECU pin No. 46.
48
No
Replace the
valve
Yes Diagnosis help
No Next step
Yes
Repair or replace
cable
CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM
No Diagnosis help
DTC: P0480 Air conditioner condenser cooling fan relay control circuit failure
No. Operating steps Result
1
2
Connect the diagnostic tester and commutator, put the
ignition switch to “OFF”
Take off the air conditioner condenser cooling fan relay;
put the ignition switch to “ON” position, and check the
voltage value by multimeter between this relay power
supply end that is relay pin No.30, No.85 and power
Yes
No Next step
supply cathode if it is around 12V.
Check if there is open circuit or short circuit to ground of
Yes
the air conditioner cooling fan relay power supply end
circuit.
No
Check the voltage by the multimeter if it is around 3.7V
4
between air conditioner condenser cooling fan relay
Yes
control ends that is relay pin No.86 and power supply
cathode.
Check if there is open circuit or short circuit to power
No Next step
Yes
supply or to ground between the circuit of relay control
end pin No.86 and ECU pin No. 50.
No
Follow up
steps
Next step
To step
No.4
Repair or
replace the
cable3
To step
No.2
Replace
relay
Repair or
replace
cable5
Diagnosis
help
DTC: P0500 Unreasonable failure of speed signal
No. Operating steps Result Follow up steps
Connect the diagnostic tester and commutator, put the
1
ignition switch to “OFF”.
Next step
Check and
2
If it is a vehicle with ABS, please check if there is
ABS DTC.
Yes
repair ABS
system
No Next step
Yes Next step
3 Check if the speedometer finger works normally.
No
Check the
speedometer
line
Yes Next step
4 Check if the speed sensor works normally.
5 Check if there is open circuit or short circuit to power
49
No
Yes Repair or
Replace speed
sensor
CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM
replace cablesupply or to ground between the circuit of speed
sensor and ECU pin No. 59.
No Diagnosis help
DTC: P0506 Rotating speed of idle speed is lower than target idle speed
No. Operating steps Result Follow up steps
1
Connect the diagnostic tester and commutator, put the
ignition switch to “OFF”.
Next step
Yes Next step
2
Check if the throttle valve adjusting screw, accelerator
cable and throttle valve working in good conditions.
No
Carry out the
necessary
repair and
maintenance
Yes Next step
Carry out the
3 Check if the idle speed regulator works in good conditions.
No
necessary
repair and
maintenance
E, check if the pressure of the fuel supplying system is too
4
low
F, check if the injector is jammed
G, check if the exhaust system is not straightway
Yes Next step
No
Replace speed
sensor
DTC: P0507 Rotating speed of idle speed is higher than target idle speed
No. Operating steps Result Follow up steps
1
Connect the diagnostic tester and commutator, put the
ignition switch to “OFF”
Next step
Yes Next step
2
Check if the throttle valve adjusting screw, accelerator
cable and throttle valve working in good conditions.
No
Carry out the
necessary repair
and
maintenance
Yes Next step
Carry out the
3 Check if the idle speed regulator works in good conditions.
No
necessary repair
and
maintenance
A, check if the system is leaking;
4
C, check if the pressure of fuel supplying system is too
B, check if the injector is leaking;
Yes
high
Carry out the
necessary repair
and
maintenance
No Diagnosis help
50
CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM
DTC: P0508 Idle speed regulator control circuit voltage is too low
No. Operating steps Result Follow up steps
1
2
Connect the diagnostic tester and commutator, put the
ignition switch to “ON”.
Take off the idle regulator joint and Check the resistance
value between idle speed regulator pin A and pin D, pin B
and pin C if it is around 53±5.3Ω when it is 20℃.
Next step
Yes Next step
No
Replace step
motor
Check if there is short circuit to ground between the circuits
3
of idle speed regulator joint pin A, B, C, D and ECU pin
No. 65, No.66, No.67. No.64.
Yes
No Diagnosis help
Repair or
replace cable
DTC: P0509 Idle speed regulator control circuit voltage is too high
No. Operating steps Result Follow up steps
1
Connect the diagnostic tester and commutator, put the
ignition switch to “ON”.
Take off the idle regulator joint and check the resistance
Next step
Yes Next step
value by multimeter separately between idle speed regulator
2
3
pin Aand pin D, pin B and pin C if it is around 53±5.3Ω
when it is 20℃.
Check using multimeter separately if there is short circuit to
power supply between the circuits of idle speed regulator
No
Yes
Replace step
motor
Repair or
replace cable
joint pin A, B, C, D and ECU pin No. 65, No.66, No.67.
No.64.
No Diagnosis help
DTC: P0511 Idle speed regulator control circuit failure
No. Operating steps Result Follow up steps
1
Connect the diagnostic tester and commutator, put the
ignition switch to “ON”.
Take off the idle regulator joint and check the resistance
Next step
Yes Next step
value by multimeter separately between idle speed
2
3
regulator pin A and pin D, pin B and pin C if it is around
53±5.3Ω when it is 20℃.
Check using multimeter separately if there is open circuit
between the circuits of idle speed regulator joint pin A, B,
C, D and ECU pin No. 65, No.66, No.67. No.64.
No
Yes
Replace step
motor
Repair or
replace cable
No Diagnosis help
DTC: P0560 System voltage signal unreasonable
No. Operating steps Result Follow up steps
1
Connect the diagnostic tester and commutator, put the
ignition switch to “OFF”.
51
Next step
CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM
Check the accumulator voltage by multimeter if it is around
2
12V.
Check if there is open circuit or short circuit to ground
3
between the circuits of ECU pin No.44, No.45, No.63 and
main relay pin No.87.
Start the engine and check if the entire generator recharging
4
5
voltage is around 9-16V at the different engine speed.
Check the engine cable harness contact position if it is in
good conditions.
Yes Next step
No
Yes
Replace
accumulator
Repair or
replace cable
No Next step
Yes Next step
No
Replace
generator
Yes Diagnosis help
No
Repair or
replace cable
DTC: P0562 System voltage is too low
No. Operating steps Result Follow up steps
1
2
3
Connect the diagnostic tester and commutator, put the
ignition switch to “OFF”.
Check the accumulator voltage by the multimeter and
observe if it is around 12V.
Check if the resistance is over big between the circuits of
ECU pin No.44, No.45, No.63 and main relay pin No.87.
Yes Next step
No
Yes
Next step
Replace
accumulator
Repair or
replace cable
No Next step
Start the engine and check if the entire generator recharging
4
5
voltage is around 9-16V at the different engine speed.
Check the engine cable harness contact position if it is in
good conditions.
Yes Next step
No
Replace
generator
Yes Diagnosis help
No
Repair or
replace cable
DTC: P0563 System voltage is too high
No. Operating steps
1
2
Connect the diagnostic tester and commutator, put the
ignition switch to “OFF”.
Check the accumulator voltage by the multimeter and
observe if it is around 12V.
Start the engine and check if the entire generator
3
recharging voltage is around 9-16V at the different engine
speed.
4
Check the engine cable harness contact position if it is in
good conditions.
52
Resu
lt
Follow up steps
Next step
Yes Next step
No
Replace
accumulator
Yes Next step
No Replace generator
Yes Diagnosis help
No Repair or replace
CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM
cable
53
CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM
DTC: P0601 ECU testing code failure
No. Operating steps Result Follow up steps
Connect the diagnostic tester and commutator, put the
1
Clean up the DTC and check the failure once again if it
2
ignition switch to “ON”.
is a steady failure.
Yes Next step
No
Next step
System if
correct
3 Replace ECU Finish
DTC: P0602 ECU diagnosis data ID code failure
No. Operating steps Result
1
2
Connect the diagnostic tester and commutator, put the
ignition switch to “ON”.
Clean up the DTC and check the failure once again if it is
a steady failure.
Yes Next step
No
3 Replace ECU Finish
DTC: P0645 Air conditioner compressor relay control circuit failure
No. Operating steps Result
1
2
Connect the diagnostic tester and commutator, put the
ignition switch to “OFF”.
Take off air conditioner compressor relay; put ignition
switch to “ON”; check the voltage value between relay
Yes
power supply ends that relay pin No.30, No.85 and
power cathode and observe if it is around 12V.
Check if there is open circuit or short circuit to ground
No Next step
Yes
of the relay power supplying ends circuit.
No
Check the voltage value by the multimeter between air
4
conditioner compressor relay control ends that is relay
Yes
pin No.86 and power cathode and observe if it is around
3.7V.
Check if there is open circuit between the circuit of air
5
conditioner compressor relay control ends that is relay
No Next step
Yes
pin No.86 and ECU pin No.70.
No
Follow up
steps
Next step
System if
correct
Follow up
steps
Next step
To step
No.4
Repair or
replace
cable3
To step
No.2
Replace
relay
Repair or
replace
cable
Diagnosis
help
54
CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM
DTC: P0646 Much lower voltage of air conditioner compressor relay control circuit
No. Operating steps Result Follow up steps
1
2
Connect the diagnostic tester and commutator, put the
ignition switch to “OFF”.
Take off air conditioner compressor relay; put ignition
switch to “ON”; check the voltage value between relay
power supply ends that relay pin No.30, No.85 and
Next step
Yes To step No.4
No Next step
power cathode and observe if it is around 12V.
Check if there is open circuit or short circuit to ground of
3
the relay power supplying ends circuit.
Yes
Repair or
replace cable
No To step No.2
Check the voltage value by the multimeter between air
4
conditioner compressor relay control ends that is relay
pin No.86 and power cathode and observe if it is around
Yes Replace relay
No Next step
3.7V.
Check if there is short circuit to ground between the
5
circuit of air conditioner compressor relay control ends
that is relay pin No.86 and ECU pin No.70.
Yes
No Diagnosis help
Repair or
replace cable
DTC: P0647 Much higher voltage of air conditioner compressor relay control circuit
No. Operating steps Result
1
2
Connect the diagnostic tester and commutator, put the
ignition switch to “OFF”.
Take off air conditioner compressor relay; put ignition
switch to “ON”; check the voltage value between relay
power supply ends that relay pin No.30, No.85 and
Yes To step No.4
No Next step
Follow up
steps
Next step
power cathode and observe if it is around 12V.
Check if there is open circuit or short circuit to ground of
3
the relay power supplying ends circuit.
Yes
Repair or
replace cable
No To step No.2
Check the voltage value by the multimeter between air
4
conditioner compressor relay control ends that is relay
pin No.86 and power cathode and observe if it is around
Yes Replace relay
No Next step
3.7V.
5
Check if there is short circuit to power supply between
the circuit of air conditioner compressor relay control
ends that is relay pin No.86 and ECU pin No.70.
Yes
No
Repair or
replace cable
Diagnosis
help
55
CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM
DTC: P1651 Trouble light control circuit failure
No. Operating steps Result
1
2
Connect the diagnostic tester and commutator, put the
ignition switch to “ON”.
Carry out action test to engine trouble light by using
diagnostic meter “actuator action test” item; and observe
the indicator if it is always at the status of extinguishing or
Yes Next step
No
lighting on.
3
Check if there is open circuit or short circuit to ground of
the engine trouble light power supplying circuit.
Yes
No Next step
Check if there is open circuit or short circuit to power
4
supply or short circuit to ground between the circuit of
engine trouble light control ends and ECU pin No. 28.
Yes
No
5. TYPICAL FAILURE AND ITS DIAGNOSIS FLOW
5.1 EXPLANATION
Follow up
steps
Next step
System is
correct
Repair or
replace cable
Repair or
replace cable
Diagnosis
help
Carry out the primary inspection before start the diagnosing according to the engine failure
phenomenon.
1) Make sure the engine trouble light is working properly;
2) Make sure that there is no failure information record checked by diagnostic meter;
3) Make sure that the failure phenomenon exists according to the customers’complaints , and
confirm the conditions causing the failure.
Then carry out the exterior inspection:
（1）
（2）
（3）
（4）
Check if there is any fuel pipe is leaking;
Check if the vacuum pipe is broken, kinked up or linked correctly;
Check if the air intake pipe is jammed, leaking, staved or damaged;
Check the high voltage line of ignition system if it is broken or aging and if the
（5）
ignition order is correct;
Check the cable grounding place if it is clean and fastness;
56
CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM
（6）
Check the sensor and actuator joint if it is loosening or bad contact.
Important notice: if the above phenomenon is appeared, you should repair the above the
failure at first otherwise it will influence the later service.
Diagnosis help:1 Confirm there is no engine failure record;
2 Confirm that the failure exists before the customer complaints;
3 Inspect the engine according to the above steps and find nothing wrong;
4 During the service please do not ignore the influence from vehicle
maintenance, cylinder pressure, mechanical ignition timing and fuel
conditions;
5 Replace ECU and carry out test. If the failure is deleted, the failure is in
ECU; if the failure can not be deleted, replace back to the original ECU and
repeat the flow and check and repair it again.
5.2 TYPICAL FAILURE DIAGNOSIS FLOW
1. The engine does not rotate or rotate slowly when it is started
The normal failure component: 1) accumulator; 2) starting motor; 3) cable or ignition
switch; 4) mechanical part of the engine.
The general diagnosis flow:
No. Operating steps Result Follow up steps
Check the voltage value between the two wiring terminals
1
of the accumulator by multimeter; check if it is around
8-12V when the engine is starting.
Put the ignition switch at start position, checking the anode
2
terminal of starting motor by multimeter and observe the
voltage if it is above 8V.
Yes Next step
No
Replace
accumulator
Yes Next step
No
Repair or
replace cable
Repair or
Disassemble the starting motor and check its working
3
conditions. Check if there is open circuit or jammed by
Yes
replace starting
motor
poor lubricating.
No Next step
4
If the failure is happened in winter time, check if it is
because of the wrong engine lubricant and gearbox oil
Yes
causes the big resistance of the starting motor.
Change to
correct
lubricant
No Next step
Repair the
Check the mechanical resistance inside of the engine if it is
too big causes the starting motor can not rotate or rotate
slowly.
Yes
No
engine inside
resistance5
Repeat the
above steps
57
CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM
2. The engine can draw rotating but can not start successfully when it is started.
General failure component: 1) no fuel in fuel tank; 2) fuel pump; 3) speed sensor; 4)
ignition coil; 5) engine mechanical part.
Diagnosis flow:
No. Operating steps Result Follow up steps
Connect the fuel pressure meter ( connecting point is
Yes Next step
the front end of fuel distributing pipe assembly fuel
1
intake pipe); starting the engine by starter and check
fuel pressure if it is around 260kpa; take off the
No
vacuum pipe from fuel pressure regulator check the
Repair the fuel
supplying
system
fuel pressure if it is around 300kpa.
Connect EFI diagnostic meter; observe “engine speed”
2
data item and start the engine and check if there is
rotation speed signal is output.
Pull off one of the cylinder separating line and take off
this cylinder injector joint and connect spark plug to it;
3
keep the spark electrode around 5mm away from
engine body; start the engine by starter and check if
there is blue and white high pressure fire.
4 Check the pressure of each engine cylinder; check if
there is engine cylinder insufficient pressure.
Check if the power supply to ECU pin No.12, 13, 44,
5
45, 63 is correct; check if the pin armature of No. 3,
51, 53, 61, 80 are working correctly.
Yes Next step
No
Repair the
sensor cable
Yes Next step
No
Repair the
ignition system
Eliminate
Yes
engine
mechanical
failure
No Next step
Yes Diagnosis help
Check the
No
corresponding
line
58
CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM
3. It is hard to start the heating car.
General failure component: 1) water inside of fuel; 2) fuel pump; 3) coolant
temperature sensor; 4) fuel pressure regulator vacuum pipe; 5) ignition coil.
General diagnostic flow
No. Operating steps Result
Connect the fuel pressure meter ( connecting point is the
Yes Next step
front end of fuel distributing pipe assembly fuel intake
1
pipe); starting the engine and check fuel pressure at idle
speed if it is around 260kpa; take off the vacuum pipe
No
from fuel pressure regulator check the fuel pressure if it
is around 300kpa.
Pull off one of the cylinder separating line and connect
2
spark plug to it; keep the spark electrode around 5mm
away from engine body; start the engine and check if
Yes Next step
No
there is blue and white high pressure fire.
Take off the coolant temperature sensor joint and start
3
the engine; observe if the engine can be started
Yes
successfully. (or serial connecting a 300Ωresistance at
the joint of coolant temperature sensor; observe if we
can start the engine)
4
Check if there if loosen or leaking of the fuel pressure
regulator vacuum pipe..
No Next step
Yes
No Next step
Follow up
steps
Repair the
fuel supplying
system
Repair the
ignition
system
Repair circuit
or replace
sensor
Repair or
replace
5
Check fuel conditions and check if the failure is
appeared after the fuel refilling
Connect EFI system adaptor, turn on the ignition switch;
6
check the power supply of pin No.12, 13, 44, 45 and
No.63 if it is in right conditions; check pin armature of
No.3, 51, 53, 61 and No.80 if it is in right conditions.
Yes Change fuel
No
Yes
Diagnosis
help
Diagnosis
help
Check
correspond
circuit
59
CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM
4. It’s hard to start the cold car.
General failure component: 1), water in the fuel; 2), fuel pump; 3), coolant temperature
sensor; 4), injector; 5), ignition coil; 6), throttle valve and idle speed by pass port; 7),
engine mechanical part.
General diagnosis flow:
No. Operating steps Result Follow up steps
Connect the fuel pressure meter ( connecting point is the
Yes Next step
front end of fuel distributing pipe assembly fuel intake
1
pipe); start the engine and check fuel pressure at idle
speed if it is around 260kpa; take off the vacuum pipe
from fuel pressure regulator check the fuel pressure if it
No
Repair the fuel
supplying system
is around 300kpa.
Pull off one of the cylinder separating line and connect
2
spark plug to it; keep the spark electrode around 5mm
away from engine body; start the engine and check if
there is blue and white high pressure fire.
Take off the coolant temperature sensor joint and start the
engine; observe if the engine can be started successfully.
3
Yes Next step
No
Yes
Check and repair
ignition system
Repair circuit or
replace sensor
(or serial connecting a 2500Ωresistance at the joint of
coolant temperature sensor; observe if we can start the
No Next step
engine)
Clean throttle
Step on the accelerator slightly and observe if it is easy to
4
be started
Yes
valve and idle
speed air port
No Next step
Disassemble the injector, check the injector using the
5
injector special cleaning analysis meter and observe if it
is leaking or jammed.
Check fuel conditions and check if the failure is appeared
6
Check pressure conditions of every cylinder and observe
7
after the fuel refilling
if there is insufficient pressure
Connect EFI system adaptor, turn on the ignition switch;
8
check the power supply of pin No.12, 13, 44, 45 and
No.63 if it is in right conditions; check pin armature of
No.3, 51, 53, 61 and No.80 if it is in right conditions.
Yes Replace the part
No Next step
Yes Change fuel
No Next step
Yes Trouble shoot
No Next step
Yes Diagnosis help
No
Check correspond
circuit
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CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM
5. Normal engine speed but hard to start at any time.
General failure component: 1), water in fuel; 2), fuel pump; 3), coolant temperature
sensor; 4), injector; 5), ignition coil; 6), throttle valve and idle speed by pass port; 7), air
intake port; 8), ignition timing; 9), spark plug; 10), engine mechanical part.
General diagnosis flow:
No. Operating steps Result Follow up steps
1
Check the air cleaner if it is jammed; check the air
intake port if it is leaking.
Yes
Repair the air
intake system
No Next step
Connect the fuel pressure meter ( connecting point is
Yes Next step
the front end of fuel distributing pipe assembly fuel
2
intake pipe); start the engine and check fuel pressure
at idle speed if it is around 260kpa; take off the
vacuum pipe from fuel pressure regulator check the
No
Repair the fuel
supplying system
fuel pressure if it is around 300kpa.
Pull off one of the cylinder separating line and connect
spark plug to it; keep the spark electrode around 5mm
3
away from engine body; start the engine and check if
there is blue and white high pressure fire.
4
Check spark plugs in every cylinder and observe its
type and clearance if it is accord with the regulation.
Yes Next step
No
Check and repair
ignition system
Yes Next step
No Adjust or replace
5
6
7
8
9
10
Take off the coolant temperature sensor joint and start
the engine; observe if the engine can be started
successfully.
Step on the accelerator slightly and observe if it is
easy to be started easily.
Disassemble the injector, check the injector using the
injector special cleaning analysis meter and observe if
it is leaking or jammed.
Check fuel conditions and check if the failure is
appeared after the fuel refilling
Check pressure conditions of every cylinder and
observe if there is insufficient pressure
Check the engine ignition order and ignition timing if
it is accord with the regulation.
Yes
Repair circuit or
replace sensor
No Next step
Clean throttle
Yes
valve and idle
speed air port
No Next step
Yes Replace the part
No Next step
Yes Change fuel
No Next step
Yes Trouble shoot
No Next step
Yes Next step
No
Repair the
ignition timing
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CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM
6. Regular starts but the idle speed is not steady at any time.
General failure component: 1), water in fuel; 2), injector; 3), spark plug; 4), throttle
valve and idle speed by pass port; 5), air intake port; 6), idle speed regulator; 7),
ignition timing; 8), spark plug; 9), engine mechanical.
General diagnosis flow:
No. Operating steps Result Follow up steps
Check the air cleaner if it is jammed; check the air intake
1
port if it is leaking.
Yes
Repair the air
intake system
No Next step
2 Check idle speed regulator if it is partial blocked
Yes
Clean or
replace
No Next step
3
4
Check spark plugs in every cylinder and observe its type
and clearance if it is accord with the regulation.
Check the throttle valve and idle speed by pass if there is
carbon deposition.
Yes Next step
No
Adjust or
replace
Yes Cleaning
No Next step
Disassemble the injector, check the injector using the
5
injector special cleaning analysis meter and observe if it is
leaking or jammed.
Check fuel conditions and check if the failure is appeared
6
Check pressure conditions of every cylinder and observe if
7
8
there is big pressure difference between the cylinders.
Check the engine ignition order and ignition timing if it is
after the fuel refilling
accord with the regulation.
Connect EFI system adaptor, turn on the ignition switch;
check the power supply of pin No.12, 13, 44, 45 and No.63
9
if it is in right conditions; check pin armature of No.3, 51,
53, 61 and No.80 if it is in right conditions.
Yes Replace part
No Next step
Yes Change fuel
No Next step
Yes Trouble shoot
No Next step
Yes Next step
No
Repair the
ignition timing
Yes Diagnosis help
Repair the
No
corresponding
line
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CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM
7. Regular starts but the idle speed is not steady during engine heating.
General failure component: 1), water in fuel; 2), coolant temperature sensor; 3), spark
plug; 4), throttle valve and idle speed by pass port; 5), air intake port; 6), idle speed
regulator; 7), engine mechanical.
General diagnosis flow:
No. Operating steps Result Follow up steps
1
Check the air cleaner if it is jammed; check the air
intake port if it is leaking.
Yes
Repair the air
intake system
No Next step
2
Check spark plugs in every cylinder and observe its
type and clearance if it is accord with the regulation.
Disassemble the idle speed regulator and check the
3
throttle valve and idle speed by pass port if there is
carbon deposition
Pull off coolant temperature sensor joint and start the
4
engine; observe the engine if it is idle speed unsteady
during warming up the engine.
Yes Next step
No Adjust or replace
Yes
Cleaning the
related parts
No Next step
Yes
Repair the line or
replace sensor
No Next step
Disassemble the injector, check the injector using the
5
injector special cleaning analysis meter and observe
if it is leaking or jammed or overflowing.
6
Check fuel conditions and check if the failure is
appeared after the fuel refilling
Check pressure conditions of every cylinder and
7
observe if there is big pressure difference between
the cylinders.
Connect EFI system adaptor, turn on the ignition
Yes Replace part
No Next step
Yes Change fuel
No Next step
Yes Trouble shoot
No Next step
Yes Diagnosis help
switch; check the power supply of pin No.12, 13, 44,
8
45 and No.63 if it is in right conditions; check pin
armature of No.3, 51, 53, 61 and No.80 if it is in
No
right conditions.
Repair the
corresponding
line
63
CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM
8. Regular starts but idle speed is not steady after the engine heating.
General failure component: 1), water in fuel; 2), coolant temperature sensor; 3), spark
plug; 4),throttle valve and idle by pass port; 5), air intake port; 6), idle speed regulator;
7), engine mechanical part.
General diagnosis flow:
No. Operating steps Result Follow up steps
1
Check the air cleaner if it is jammed; check the air intake
port if it is leaking.
Yes
Repair the air
intake system
No Next step
2
Check spark plugs in every cylinder and observe its type
and clearance if it is accord with the regulation.
Disassemble the idle speed regulator and check the throttle
3
valve and idle speed by pass port if there is carbon
deposition
Yes Next step
No
Yes
Adjust or
replace
Cleaning the
related parts
No Next step
Repair the line
Pull off coolant temperature sensor joint and start the
4
engine; observe the engine if it is idle speed unsteady
Yes
or replace
sensor
during warming up the engine.
No Next step
Disassemble the injector, check the injector using the
5
injector special cleaning analysis meter and observe if it is
leaking or jammed or overflowing.
6
7
Check fuel conditions and check if the failure is appeared
just after the fuel refilling
Check pressure conditions of every cylinder and observe if
there is big pressure difference between the cylinders.
Connect EFI system adaptor, turn on the ignition switch;
check the power supply of pin No.12, 13, 44, 45 and No.63
8
if it is in right conditions; check pin armature of No.3, 51,
53, 61 and No.80 if it is in right conditions.
Yes Replace part
No Next step
Yes Change fuel
No Next step
Yes Trouble shoot
No Next step
Yes Diagnosis help
Repair the
No
corresponding
line
64
CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM
9. Regular starts but idle speed is not steady or dying out when there is partial loading.
General failure component: 1) air conditioner system; 2) idle speed regulator; 3)
injector.
General diagnosis flow:
No. Operating steps Result Follow up steps
Disassemble the idle speed regulator and check the
1
throttle valve and idle speed by pass port if there is
carbon deposition.
Observe if the engine output power increased when
Yes
No Next step
Yes To step No.4
Cleaning the
related parts
the air conditioner is switched on, that is using EFI
2
system diagnosis meter observing ignition angle of
advance, fuel injection pulse width and changes of air
No Next step
intake flow.
Connect EFI system adaptor; break connecting line of
3
ECU pin No.75; check the cable end if it is up level
signal when the air conditioner is switched on.
Yes Next step
Repair air
No
conditioning
system
Check air conditioning system pressure; check the
4
compressor solenoid clutch and air conditioner
compressor pump fuel conditions and check if it is
working correctly.
Disassemble the injector, check the injector using the
5
injector special cleaning analysis meter and observe if
it is leaking or jammed or overflowing.
Connect EFI system adaptor, turn on the ignition
Yes Next step
No
Repair the air
conditioning sys.
Yes Replace fault part
No Next step
Yes Diagnosis help
switch; check the power supply of pin No.12, 13, 44,
6
45 and No.63 if it is in right conditions; check pin
armature of No.3, 51, 53, 61 and No.80 if it is in right
No
conditions.
Repair the
corresponding
line
65
CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM
10. Regular starts with high idle speed.
General failure component: 1) throttle valve and idle speed by pass port; 2) vacuum
pipe; 3) idle speed regulator; 4) coolant temperature sensor; 5) ignition timing.
General diagnosis flow:
No. Operating steps Result Follow up steps
1 Check accelerator cable if it is blocked or over tightening
Yes Adjust
No Next step
Repair the air
Check the air intake system and its connecting vacuum pipe
2
if it is leaking.
Yes
in taking
system
No Next step
Disassemble the idle speed regulator and check the throttle
3
valve and idle speed by pass port if there is carbon
deposition
4
5
Take off the coolant temperature sensor joint; start the
engine and observe if it has high idle speed.
Check the engine ignition timing if it is accord with the
regulations.
Connect EFI system adaptor, turn on the ignition switch;
check the power supply of pin No.12, 13, 44, 45 and No.63
6
if it is in right conditions; check pin armature of No.3, 51,
53, 61 and No.80 if it is in right conditions.
Yes
Clean related
part
No Next step
Yes
Repair line or
replace sensor
No Next step
Yes Next step
No
Repair the
ignition timing
Yes Diagnosis help
Repair the
No
corresponding
line
66
CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM
11. Low engine speed or dying out exists when it is accelerated.
General failure component: 1) water in fuel; 2) air intake pressure sensor and throttle
position sensor; 3) spark plug; 4) throttle valve and idle speed by pass port; 5) air intake
port; 6) idle speed regulator; 7) injector; 8) ignition timing; 9) exhaust pipe.
General diagnosis flow:
No. Operating steps Result Follow up steps
1 Check the air cleaner if it is jammed.
Yes
Repair the air
intake system
No Next step
Connect the fuel pressure meter ( connecting point is the
Yes Next step
front end of fuel distributing pipe assembly fuel intake
pipe); start the engine and check fuel pressure at idle speed
2
if it is around 260kpa; take off the vacuum pipe from fuel
pressure regulator check the fuel pressure if it is around
No
Repair the fuel
supplying
system
300kpa.
3
Check spark plugs in every cylinder and observe its type
and clearance if it is accord with the regulation.
Disassemble idle speed regulator and check throttle valve,
4
idle speed regulator and idle speed by pass port if there is
carbon deposition.
Yes Next step
No
Yes
Adjust or
replace
Clean related
part
No Next step
5
Inspect air intake pressure sensor, throttle position sensor
and its line if it is working correctly.
Disassemble the injector, check the injector using the
6
injector special cleaning analysis meter and observe if it is
leaking or jammed.
7
8
Check fuel conditions and check if the failure is appeared
after the fuel refilling
Check the engine ignition order and ignition timing if it is
accord with the regulation.
9 Check the exhaust pipe if the air exhausting is smooth
Connect EFI system adaptor, turn on the ignition switch;
10
check the power supply of pin No.12, 13, 44, 45 and No.63
if it is in right conditions; check pin armature of No.3, 51,
53, 61 and No.80 if it is in right conditions.
Yes Next step
No
Yes
Repair line or
replace sensor
Replace fault
part
No Next step
Yes Replace fuel
No Next step
Yes Next step
No
Repair ignition
timing
Yes Next step
Repair or
No
replace exhaust
pipe
Yes Diagnosis help
Repair
No
corresponding
line
67
CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM
12. React slowly when it is accelerated.
General failure component: 1) water in fuel; 2) air intake pressure sensor and throttle
position sensor; 3) spark plug; 4) throttle valve and idle speed by pass port; 5) air intake
port; 6) idle speed regulator; 7) injector; 8) ignition timing; 9) exhaust pipe.
General diagnosis flow:
No. Operating steps Result Follow up steps
1 Check the air cleaner if it is jammed.
Yes
Repair the air
intake system
No Next step
Connect the fuel pressure meter ( connecting point is the
Yes Next step
front end of fuel distributing pipe assembly fuel intake
pipe); start the engine and check fuel pressure at idle speed
2
if it is around 260kpa; take off the vacuum pipe from fuel
pressure regulator check the fuel pressure if it is around
No
Repair the fuel
supplying
system
300kpa.
3
Check spark plugs in every cylinder and observe its type
and clearance if it is accord with the regulation.
Disassemble idle speed regulator and check throttle valve,
4
idle speed regulator and idle speed by pass port if there is
carbon deposition.
Yes Next step
No
Yes
Adjust or
replace
Clean related
part
No Next step
5
Inspect air intake pressure sensor, throttle position sensor
and its line if it is working correctly.
Disassemble the injector, check the injector using the
6
injector special cleaning analysis meter and observe if it is
leaking or jammed.
7
8
Check fuel conditions and check if the failure is appeared
after the fuel refilling
Check the engine ignition order and ignition timing if it is
accord with the regulation.
9 Check the exhaust pipe if the air exhausting is smooth
Connect EFI system adaptor, turn on the ignition switch;
check the power supply of pin No.12, 13, 44, 45 and No.63
10
if it is in right conditions; check pin armature of No.3, 51,
53, 61 and No.80 if it is in right conditions.
Yes Next step
No
Yes
Repair line or
replace sensor
Replace fault
part
No Next step
Yes Replace fuel
No Next step
Yes Next step
No
Repair ignition
timing
Yes Next step
Repair or
No
replace exhaust
pipe
Yes Diagnosis help
Repair
No
corresponding
line
68
CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM
13. The performance is poor when it is accelerated.
General failure component:1) water in fuel; 2) air intake pressure sensor and throttle
position sensor; 3) spark plug; 4) ignition coil; 5) throttle valve and idle speed by pass
port; 6) air intake port;7) idle speed regulator; 8) injector; 9) ignition timing; 10)
exhaust pipe.
General diagnosis flow:
No. Operating steps Result
Check if there are failures like clutch skidding, low tyre
1
pressure, brake dragging, wrong tyre size, and wrong four
Yes Repair
wheel positioning etc..
2 Check the air cleaner if it is jammed.
Yes
No Next step
Connect the fuel pressure meter ( connecting point is the
Yes Next step
front end of fuel distributing pipe assembly fuel intake
pipe); start the engine and check fuel pressure at idle speed
3
if it is around 260kpa; take off the vacuum pipe from fuel
No
pressure regulator check the fuel pressure if it is around
300kpa.
Pull off one of the cylinder separating line and connect
spark plug to it; keep the spark electrode around 5mm away
4
from engine body; start the engine and check the high
Yes Next step
No
pressure fire strength if it is regular.
Check spark plugs in every cylinder and observe its type and
5
clearance if it is accord with the regulation.
Disassemble idle speed regulator and check throttle valve,
6
idle speed regulator and idle speed by pass port if there is
carbon deposition.
7
Inspect air intake pressure sensor, throttle position sensor
and its line if it is working correctly.
Disassemble the injector, check the injector using the
8
injector special cleaning analysis meter and observe if it is
leaking or jammed.
9
Check fuel conditions and check if the failure is appeared
after the fuel refilling
Yes Next step
No
Yes
No Next step
Yes Next step
No
Yes
No Next step
Yes Replace fuel
No Next step
Yes Next step
10
Check the engine ignition order and ignition timing if it is
accord with the regulation.
No
Follow up
steps
Next step
Repair the air
intake system
Repair the
fuel supplying
system
Repair
ignition
system
Adjust or
replace
Clean related
part
Repair line or
replace sensor
Replace fault
part
Repair
ignition
timing
69
CHERY·A21 SERVICE MANUAL ENGINE EFI SYSTEM
11 Check the exhaust pipe if the air exhausting is smooth
Connect EFI system adaptor, turn on the ignition switch;
12
check the power supply of pin No.12, 13, 44, 45 and No.63
if it is in right conditions; check pin armature of No.3, 51,
53, 61 and No.80 if it is in right conditions.
Yes Next step
Repair or
No
replace
exhaust pipe
Yes
Diagnosis
help
Repair
No
corresponding
line
70
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