DTC Troubleshooting

DTC P0138: Secondary HO2S (Sensor 2) Circuit High Voltage ('05-07 models)

NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information.

1. Turn the ignition switch ON (II).
2. Clear the DTC with the HDS.
3. Start the engine, and let it idle without load (in Park or neutral) until the radiator fan comes on.

4. Check the HO2S S2 in the DATA LIST with the HDS.

Does the voltage stay at 1.25 V or more?

YES - Go to step 5.

NO - Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the secondary HO2S (Sensor 2) and the ECM/PCM.

5. Turn the ignition switch OFF.
6. Disconnect the secondary HO2S (Sensor 2) 4P connector.




7. Connect secondary HO2S (Sensor 2) 4P connector terminals No. 1 and No. 2 with a jumper wire.
8. Turn the ignition switch ON (II).
9. Check the HO2S S2 in the DATA LIST with the HDS.

Does the voltage stay at 1.25 V or more?

YES - Go to step 10.

NO - Go to step 19.

10. Turn the ignition switch OFF.
11. Remove the jumper wire from the secondary HO2S (Sensor 2) 4P connector.




12. Connect secondary HO2S (Sensor 2) 4P connector terminal No. 2 to body ground with a jumper wire.
13. Turn the ignition switch ON (II).
14. Check the HO2S S2 in the DATA LIST with the HDS.

Does the voltage stay at 1.25 V or more?

YES - Go to step 15.

NO - Repair open in the wire between the ECM/PCM (E4) and the secondary HO2S (Sensor 2), then Go to step 21.

15. Turn the ignition switch OFF.
16. Jump the SCS line with the HDS.
17. Disconnect ECM/PCM connector E (31P).




18. Check for continuity between ECM/PCM connector terminal E20 and body ground.

Is there continuity?

YES - Go to step 29.

NO - Repair open in the wire between the ECM/PCM (E20) and the secondary HO2S (Sensor 2), then Go to step 21.

19. Turn the ignition switch OFF.
20. Replace the secondary HO2S (Sensor 2).
21. Reconnect all connectors.
22. Turn the ignition switch ON (II).
23. Reset the ECM/PCM with the HDS.
24. Do the ECM/PCM idle learn procedure.
25. Start the engine, and let it idle without load (in Park or neutral) until the radiator fan comes on.
26. Test-drive under these conditions:
- Engine coolant temperature (ECT SENSOR) ('05 model), Engine coolant temperature (ECT SENSOR 1) ('06-07 models) above 158 °F (70 °C)
- A/T in D position (M/T in 4th gear)
- Engine speed at 1,500 - 3,000 rpm
- Drive 1 minute or more

27. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P0138 indicated?

YES - Check for poor connections or loose terminals at the secondary HO2S (Sensor 2) and the ECM/PCM, then Go to step 1.

NO - Go to step 28.

28. Monitor the OBD STATUS for DTC P0138 in the DTCs MENU with the HDS.

Does the screen indicate PASSED?

YES - Troubleshooting is complete. If any other Temporary DTCs or DTCs were indicated in step 27, Go to the indicated DTC's troubleshooting.

NO - If the screen indicates FAILED, check for poor connections or loose terminals at the secondary HO2S (Sensor 2) and the ECM/PCM, then Go to step 1. If the screen indicates EXECUTING, keep driving until a result comes on. If the screen indicates OUT OF CONDITION, Go to step 25.

29. Reconnect all connectors.
30. Update the ECM/PCM if it does not have the latest software, or substitute a known good ECM/PCM.
31. Start the engine, and let it idle without load (in Park or neutral) until the radiator fan comes on.
32. Test-drive under these conditions:
- Engine coolant temperature (ECT SENSOR) ('05 model), Engine coolant temperature (ECT SENSOR 1) ('06-07 models) above 158 °F(70 °C)
- A/T in 0 position (M/T in 4th gear)
- Engine speed at 1,500 - 3,000 rpm
- Drive 1 minute or more

33. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P0138 indicated?

YES - Check for poor connections or loose terminals at the secondary HO2S (Sensor 2) and the ECM/PCM. If the ECM/PCM was updated, substitute a known good ECM/PCM, then Go to step 31. If the ECM/PCM was substituted, Go to step 1.

NO - Go to step 34.

34. Monitor the OBD STATUS for DTC P0138 in the DTCs. MENU with the HDS.

Does the screen indicate PASSED?

YES - If the ECM/PCM was updated, troubleshooting is complete. If the ECM/PCM was substituted, replace the original ECM/PCM. If any other Temporary DTCs or DTC's were indicated in step 33, Go to the indicated DTC's troubleshooting.

NO - If the screen indicates FAILED,check for poor connections or loose terminals at secondary HO2S (Sensor 2) and the ECM/PCM. If the ECM/PCM was updated, substitute a known good ECM/PCM, then Go to step 31. If the ECM/PCM was substituted, Go to step 1. If the screen indicates EXECUTING, keep driving until a result comes on. If the screen indicates OUT OF CONDITION, Go to step 31.