P0137

DTC P0137: Secondary HO2S (Sensor 2) Circuit Low Voltage

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 0.3 V or less?

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. Start the engine.
7. Check the secondary HO2S (Sensor 2) output voltage with a scan tool or the HDS.

Does the voltage stay at 0.3 V or less?

YES - Go to step 8.

NO - Replace the secondary HO2S (Sensor 2)*.

8. Turn the ignition switch OFF.
9. Disconnect ECM connector C (31P).




10. Check for continuity between secondary HO2S (Sensor 2) 4P connector terminal No. 2 and body ground.

Is there continuity?

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

NO - Substitute a known-good ECM and recheck. If the symptom/indication goes away, replace the original ECM.