DTC Troubleshooting

Control System DTCs

DTC Troubleshooting: P0139

DTC P0139 : Secondary HO2S (Sensor 2) Slow Response

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.
* If the exhaust leaks from the exhaust system, this DTC will be set. Check for damage in the exhaust pipe, and repair it if needed.


1. Problem verification:

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

-2. Clear the DTC with the HDS. How to Troubleshoot the Fuel And Emissions Systems

-3. Start the engine. Hold the engine speed at 3,000 rpm without load (in P or N) until the radiator fan comes on, then let it idle.

-4. Test-drive under these conditions:
* Engine coolant temperature (ECT SENSOR 1) above 158 °F (70 °C)
* Transmission in D
* Drive at a steady speed between 55-75 mph (90-120 km/h) for 1 minute, then decelerate (with the throttle fully closed) for 10 seconds





-5. Monitor the OBD STATUS for DTC P0139 with the HDS.





Does the HDS indicate FAILED?
-YES- The failure is duplicated. Replace secondary HO2S (Sensor 2) Secondary HO2S Removal And Installation, then do the repair verification.
-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 PCM. If the HDS indicates EXECUTING, keep driving until a result comes on. If the HDS indicates OUT OF CONDITION, go to step 1-3 on this step and recheck.

Repair verification (OBD STATUS check):

-1. Turn the ignition switch to LOCK (0).

-2. Reconnect all connectors.

-3. Turn the ignition switch to ON (II).

-4. Reset the PCM with the HDS How to Troubleshoot the Fuel And Emissions Systems.

-5. Do the PCM idle learn procedure PCM Idle Learn Procedure.

-6. Start the engine. Hold the engine speed at 3,000 rpm without load (in P or N) until the radiator fan comes on, then let it idle.

-7. Test-drive under these conditions:
* Engine coolant temperature (ECT SENSOR 1) above 158 °F (70 °C)
* Transmission in D
* Drive at a steady speed between 55-75 mph (90-120 km/h) for 1 minute, then decelerate (with the throttle fully closed) for 10 seconds





-8. Monitor the OBD STATUS for DTC P0139 with the HDS.






Does the HDS indicate PASSED, FAILED, EXECUTING, or OUT OF CONDITION?
-PASSED- Troubleshooting is complete. If any other Pending or Confirmed DTCs were indicated, go to the indicated DTC's troubleshooting.
-FAILED- Go to step 1 and recheck.
-EXECUTING- Keep the test condition until a result comes on.
-OUT OF CONDITION- Meet the test condition, and check the OBD STATUS again.