DTC Troubleshooting

Control System DTCs

DTC Troubleshooting: P0137

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

NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information How To Troubleshoot The Fuel And Emissions Systems.

1. Problem verification:

Problem verification
-1. Turn the ignition switch to ON (II).

-2. Clear the DTC with the HDS.

-3. Start the engine. Hold the engine speed at 3,000 rpm without load (A/T in P or N, M/T in neutral) until the radiator fan comes on.

-4. Monitor the OBD STATUS for DTC P0137 in the DTCs MENU with the HDS.

Does the HDS indicate FAILED?
-YES- The failure is duplicated. Go to step 2.
-NO- If the HDS indicates PASSED, intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at secondary HO2S (Sensor 2) and the ECM/PCM. If the HDS indicates EXECUTING, keep idling until a result comes on. If the HDS indicates OUT OF CONDITION, go to step 1-3 and recheck.

2. Shorted wire check (SO2_SG line):

Shorted wire check (SO2_SG line)
-1. Turn the ignition switch to LOCK (0).

-2. Jump the SCS line with the HDS.

-3. Disconnect the following connector.





-4. Check for continuity between test points 1 and 2.









Is there continuity?
-YES- Repair a short in the SO2_SG wire between the ECM/PCM (C47) and secondary HO2S (Sensor 2), then do the repair verification.
-NO- The SO2_SG wire is not open. Go to step 3.

3. Shorted wire check (SO2 line):

Shorted wire check (SO2 line)
-1. Disconnect the following connector.





-2. Check for continuity between test points 1 and 2.









Is there continuity?
-YES- Repair a short in the SO2 wire between the ECM/PCM (B46) and secondary HO2S (Sensor 2), then do the repair verification.
-NO- The SO2 wire is OK. Update the ECM/PCM ECM/PCM Update if it does not have the latest software, or substitute a known-good ECM/PCM Service and Repair, then do the repair verification.

Repair verification (OBD STATUS check):

-1. Reconnect all connectors.

-2. Turn the ignition switch to ON (II).

-3. Reset the ECM/PCM with the HDS How To Troubleshoot The Fuel And Emissions Systems.

-4. Do the ECM/PCM idle learn procedure. ECM/PCM Idle Learn Procedure

-5. Start the engine, and let it idle without load (A/T in P or N, M/T in neutral) until the radiator fan comes on, then let it idle.

-6. Monitor the OBD STATUS for DTC P0137 in the DTCs MENU with the HDS.

Does the HDS indicate PASSED, FAILED, EXECUTING, or OUT OF CONDITION?
-PASSED- Troubleshooting is complete. If the ECM/PCM was substituted, replace the original ECM/PCM Service and Repair. If any other Pending or Confirmed DTCs were indicated, go to the indicated DTC's troubleshooting.
-FAILED- Go to step 1 and recheck. If the ECM/PCM was updated, substitute a known-good ECM/PCM Service and Repair, then check the OBD STATUS again.
-EXECUTING- Keep the test condition until a result comes on.
-OUT OF CONDITION- Meet the test condition, and check the OBD STATUS again.