DTC Troubleshooting

DTC Troubleshooting: P2270, P2271, P2270, P2271

DTC P2270:

Secondary HO2S (Sensor 2) Circuit Signal Stuck Lean

DTC P2271:

Secondary HO2S (Sensor 2) Circuit Signal Stuck Rich

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 (A/T in P or N, M/T in neutral) 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)
- Vehicle speed at 35 mph (56 km/h) or more for at least 25 seconds

5. Monitor the OBD STATUS for DTC P2270 or P2271 in the DTCs MENU with the HDS.

Does the screen indicate FAILED?

YES -

Go to step 6.

NO -

If the screen 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 screen indicates NOT COMPLETED, go to step 3 and recheck.

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

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

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

9. Reset the ECM/PCM with the HDS.

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

11. 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, them let it idle.

12. Test-drive under these conditions:

- Engine coolant temperature (ECT SENSOR 1) above 158 °F (70 °C)
- Vehicle speed at 35 mph (56 km/h) or more for at least 25 seconds

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

Is DTC P2270 or P2271 indicated?

YES -

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

NO -

Go to step 14.

14. Monitor the OBD STATUS for DTC P2270 or P2271 in the DTCs MENU with the HDS.

Does the screen 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 screen indicates FAILED, check for poor connections or loose terminals at secondary HO2S (Sensor 2) and the ECM/PCM, then go to step 1. If the screen indicates NOT COMPLETED, go to step 11.