P0138

DTC P0138: Secondary HO2S (Sensor 2) Circuit High Voltage (2005 model)

NOTE: Before you troubleshoot, record all freeze data and review the general troubleshooting information.

1. Reset the ECM.
2. Start the engine. Hold the engine speed at 3,000 rpm without load (in neutral) until the radiator fan comes on.
3. Check the secondary HO2S (Sensor 2) output voltage at 3,000 rpm with a scan tool or the HDS.

Does the voltage stay at 3.0 V or more?

YES - Go to step 4.

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

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




6. Connect secondary HO2S (Sensor 2) 4P connector terminals No. 1 and No. 2 with a jumper wire.
7. Turn the ignition switch ON (II).
8. Check the secondary HO2S (Sensor 2) output voltage with a scan tool or the HDS.

Is there 3.0 V or more?

YES - Go to step 9.

NO - Replace the secondary HO2S (Sensor 2).

9. Turn the ignition switch OFF.
10. Disconnect the jumper wire.




11. Connect ECM connector terminals C15 and C18 with a jumper wire.
12. Turn the ignition switch ON (II).
13. Check the secondary HO2S (Sensor 2) output voltage with a scan tool or the HDS.

Is there 3.0 V or more?

YES - Substitute a known-good ECM and recheck. If the symptom/indication goes away, replace the original ECM.

NO - Go to step 14.

14. Turn the ignition switch OFF.
15. Disconnect the jumper wire.




16. Connect secondary HO2S (Sensor 2) 4P connector terminal No. 2 to body ground with a jumper wire.
17. Check the secondary HO2S (Sensor 2) output voltage with a scan tool or the HDS.

Is there 3.0 V or more?

YES - Repair open in the wire between the ECM (C15) and the secondary HO2S (Sensor 2).

NO - Go to step 18.

18. Turn the ignition switch OFF.
19. Disconnect the jumper wire.
20. Disconnect ECM connector C (31P).




21. Connect secondary HO2S (Sensor 2) 4P connector terminal No. 1 to body ground with a jumper wire.




22. Check for continuity between ECM connector terminal C18 and body ground.

Is there continuity?

YES - Substitute a known-good ECM and recheck. If the symptom/indication goes away, replace the original ECM.

NO - Repair open in the wire between the ECM (C18) and the secondary HO2S (Sensor 2).