DI–56
–DIAGNOSTICS ENGINE
DTC P0135 Heated Oxygen Sensor Heater Circuit
Malfunction (Bank1 Sensor1)
DTC P0141 Heated Oxygen Sensor Heated Circuit
Malfunction (Bank1 Sensor2)
CIRCUIT DESCRIPTION
Refer to DTC P0125 (Insufficient Coolant Temp. for Closed Loop Fuel Control) on page DI–44.
DTC No. DTC Detecting Condition Trouble Area
When the heater operates, heater current exceeds 2 A
P0135
P0141
(2 trip detection logic)
Heater current of 0.2 A or less when the heater operates
(2 trip detection logic)
HINT:
S Bank 1 refers to the bank that includes cylinder No.1.
S Sensor 1 refers to the sensor closer to the engine body.
S Sensor 2 refers to the sensor farther away from the engine body.
S Open or short in heater circuit of heated oxygen sensor
S Heated oxygen sensor heater
S ECM
DI1ED–07
WIRING DIAGRAM
Refer to DTC P0125 on page DI–44 for the WIRING DIAGRAM.
INSPECTION PROCEDURE
HINT:
Read freeze frame data using T OYOTA hand–held tester or OBD II scan tool. Because freeze frame records
the engine conditions when the malfunction is detected, when troubleshooting it is useful for determining
whether the vehicle was running or stopped, the engine warmed up or not, the air–fuel ratio lean or rich, etc.
at the time of the malfunction.
2000 CELICA (RM744U)
–DIAGNOSTICS ENGINE
1 Check voltage between terminals HT1, HT2 of ECM connectors and body
ground.
DI–57
ON
PREPARATION:
(a) Remove the ECM cover.
HT1A
(b) Remove the 3 bolts from ECM.
(c) Turn the ignition switch ON.
CHECK:
Measure voltage between terminals HT1A, HT1B of ECM connectors and body ground.
HINT:
S Connect terminal HT1A to bank 1 sensor 1.
S Connect terminal HT1B to bank 1 sensor 2.
A09084
HT1B
A09092
OK:
Voltage: 9 – 14 V
OK Check and replace ECM (See page IN–30).
NG
2 Check resistance of heated oxygen sensor heater (See page SF–70).
NG Replace heated oxygen sensor.
OK
Check and repair harness or connector between EFI main relay (Marking: EFI), heated oxygen
sensor and ECM (See page IN–30).
2000 CELICA (RM744U)