DTC Troubleshooting
DTC Troubleshooting: P0138
DTC P0138:
Secondary HO2S (Sensor 2) Circuit High Voltage
NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information.
1. Turn the ignition switch to ON (II).
2. Clear the DTC with the HDS.
3. Start the engine, and let it idle without load (in P or N) until the radiator fan comes on.
4. Check HO2S S2 in the DATA LIST with the HDS.
Does the voltage stay at 1.27 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 secondary HO2S (Sensor 2) and the PCM.�
5. Turn the ignition switch to LOCK (0).
6. Remove the cowl cover and the under-cowl panel Service and Repair.
7. Disconnect the secondary HO2S (Sensor 2) 4P connector.
8. Connect secondary HO2S (Sensor 2) 4P connector terminals No. 1 and No. 2 with a jumper wire.
9. Turn the ignition switch to ON (II).
10. Check HO2S S2 in the DATA LIST with the HDS.
Does the voltage stay at 1.27 V or more?
YES -
Go to step 11.
NO -
Go to step 20.
11. Turn the ignition switch to LOCK (0).
12. Remove the jumper wire from the secondary HO2S (Sensor 2) 4P connector.
13. Connect secondary HO2S (Sensor 2) 4P connector terminal No. 2 to body ground with a jumper wire.
14. Turn the ignition switch to ON (II).
15. Check HO2S S2 in the DATA LIST with the HDS.
Does the voltage stay at 1.27 V or more?
YES -
Go to step 16.
NO -
Repair an open in the wire between the PCM (C27) and secondary HO2S (Sensor 2), then go to step 22.
16. Turn the ignition switch to LOCK (0).
17. Jump the SCS line with the HDS.
18. Disconnect PCM connector C (44P).
19. Check for continuity between PCM connector terminal C27 and body ground.
Is there continuity?
YES -
Go to step 30.
NO -
Repair an open in the wire between the PCM (C27) and secondary HO2S (Sensor 2), then go to step 22.
20. Turn the ignition switch to LOCK (0).
21. Replace secondary HO2S (Sensor 2) Secondary HO2S Replacement.
22. Reconnect all connectors.
23. Turn the ignition switch to ON (II).
24. Reset the PCM with the HDS.
25. Do the PCM idle learn procedure PCM Idle Learn Procedure.
26. Start the engine, and let it idle without load (in P or N) until the radiator fan comes on.
27. Test-drive under these conditions:
- Engine coolant temperature (ECT SENSOR 1) above 158 °F (70 °C)
- Transmission in D
- Engine speed between 1,500-3,000 rpm
- Drive 1 minute or more
28. Check for Pending or Confirmed DTCs with the HDS.
Is DTC P0138 indicated?
YES -
Check for poor connections or loose terminals at secondary HO2S (Sensor 2) and the PCM, then go to step 1.
NO -
Go to step 29.
29. Monitor the OBD STATUS for DTC P0138 in the DTCs MENU with the HDS.
Does the HDS indicate PASSED?
YES -
Troubleshooting is complete. If any other Pending or Confirmed DTCs were indicated in step 28, go to the indicated DTC's troubleshooting.�
NO -
If the HDS indicates FAILED, check for poor connections or loose terminals at secondary HO2S (Sensor 2) and the PCM, then go to step 1. If the HDS indicates EXECUTING, keep driving until a result comes on. If the HDS indicates OUT OF CONDITION, go to step 26.
30. Reconnect all connectors.
31. Update the PCM if it does not have the latest software PCM Update, or substitute a known-good PCM.
32. Start the engine, and let it idle without load (in P or N) until the radiator fan comes on.
33. Test-drive under these conditions:
- Engine coolant temperature (ECT SENSOR 1) above 158 °F (70 °C)
- Transmission in D
- Engine speed between 1,500-3,000 rpm
- Drive about 1 minute or more
34. Check for Pending or Confirmed DTCs with the HDS.
Is DTC P0138 indicated?
YES -
Check for poor connections or loose terminals at secondary HO2S (Sensor 2) and the PCM. If the PCM was updated, substitute a known-good PCM, then go to step 32. If the PCM was substituted, go to step 1.
NO -
Go to step 35.
35. Monitor the OBD STATUS for DTC P0138 in the DTCs MENU with the HDS.
Does the HDS indicate PASSED?
YES -
If the PCM was updated, troubleshooting is complete. If the PCM was substituted, replace the original PCM Service and Repair. If any other Pending or Confirmed DTCs were indicated in step 34, go to the indicated DTC's troubleshooting.�
NO -
If the HDS indicates FAILED, check for poor connections or loose terminals at secondary HO2S (Sensor 2) and the PCM. If the PCM was updated, substitute a known-good PCM, then go to step 32. If the PCM was substituted, go to step 1. If the HDS indicates EXECUTING, keep driving until a result comes on. If the HDS indicates OUT OF CONDITION, go to step 32.