P0138

DTC P0137 / P0138

DTC Detecting Condition and Trouble Area






Wiring Diagram

Refer to P0037 DTC P0037 / P0038 / P0054.

DTC Confirmation Procedure

WARNING:

If you do not select a suitable route and take proper precautions when performing a road test, an accident can occur.

- Select a level road with no traffic to minimize the risk of accident.
- Perform the test extremely carefully.
- Perform the road test using 2 persons, a driver and an assistant.

NOTE:

If DTCs other than aimed DTC are previously detected in DTC confirmation procedure, be sure to troubleshoot DTC previously detected.

1) Warm up engine to normal operating temperature.
2) Drive vehicle at 50 - 60 km/h (31 - 37 mile/h) for 3 min. (Keep throttle valve opening constantly in this step.)

DTC Troubleshooting

1.
Was "Engine and Emission Control System Check" performed?
YES -
Go to Step 2.
NO -
Go to Engine and Emission Control System Check Engine and Emission Control System Check.

2. DTC Check

Is there any DTC(s) other than P0137 and P0138?
YES -
Go to troubleshooting for applicable DTC.
NO -
Go to Step 3.

3. HO2S signal circuit and ground circuit check

Turn OFF ignition switch and disconnect connectors from HO2S and ECM.
Check for proper terminal connection to HO2S and ECM connectors.
If connections are OK, check that HO2S signal circuit (A3) and ground circuit (A4) are as follows.
- Wiring harness resistance of each HO2S signal circuit and ground circuit is less than 3 ohms.
- Insulation resistance of HO2S signal circuit and ground circuit is infinity between HO2S connector and vehicle body ground.
- Insulation resistance of wire harness is infinity between HO2S signal terminal and each other terminal at HO2S connector.
- Insulation resistance of wire harness is infinity between HO2S ground circuit terminal and each other terminal.
- Circuit voltage of HO2S signal circuit and ground circuit is 0 - 1 V with ignition switch in ON position.

Are they in good condition?
YES -
Go to Step 4.
NO -
Repair or replace defective wire harness.

4. Exhaust system and air intake system check

Check exhaust system and air intake system for clogging or leak.

Is it in good condition?
YES -
Go to Step 5.
NO -
Repair or replace defective part.

5. HO2S heater circuit check

Check HO2S heater circuit according to Step 2 through Step 3 under P0037 DTC P0037 / P0038 / P0054.

Is circuit in good condition?
YES -
Go to Step 6.
NO -
Repair or replace defective part.

6. DTC recheck

Replace HO2S. Heated Oxygen Sensor (HO2S) Removal and Installation
Perform DTC confirmation procedure and check DTC.

Is DTC P0137 or P0138 still detected?
YES -
Substitute a known-good ECM and recheck.
NO -
End.