DTC Troubleshooting

DTC Troubleshooting: P0139 (63)

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 Initial Inspection and Diagnostic Overview.

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 (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 at 30 mph (48 km/h) or more for 20 seconds.

5. Monitor the OBD STATUS for DTC P0139 in the DTCs MENU with the HDS.

Does the HDS indicate FAILED?

YES -

Go to step 6.

NO -

If the HDS indicates PASSED, intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the 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 3 and recheck.

6. Turn the ignition switch to LOCK (0).

7. Replace the secondary HO2S (Sensor 2) Secondary HO2S Replacement.

8. Turn the ignition switch to ON (II).

9. Reset the PCM with the HDS.

10. Do the PCM idle learn procedure PCM Idle Learn Procedure.

11. 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.

12. Test-drive under these conditions:

- Engine coolant temperature (ECT SENSOR 1) above 158 °F (70 °C)
- Transmission in D
- Drive at a steady speed at 30 mph (48 km/h) or more for 20 seconds

13. Check for Pending or Confirmed DTCs with the HDS.

Is DTC P0139 indicated?

YES -

Check for poor connections or loose terminals at the secondary HO2S (Sensor 2) and the PCM, then go to step 1.

NO -

Go to step 14.

14. Monitor the OBD STATUS for DTC P0139 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 13, go to the indicated DTC's troubleshooting.

NO -

If the HDS indicates FAILED, check for poor connections or loose terminals at the 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 11.