DTC Troubleshooting

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.

1. Turn the ignition switch ON (II).
2. Clear the DTC with the HDS.
3. Start the engine, and let it idle without load (in Park or neutral) until the radiator fan comes on.
4. Test-drive under these conditions:
- ECT SENSOR 1 above 158 °F (70 °C)
- Vehicle speed at 35 mph (56 km/h) or more for at least 23 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, system is OK at this time. Check for poor connections or loose terminals at the secondary HO2S (Sensor 2) and the ECM/PCM. If the screen indicates EXECUTING, keep driving until a result comes on. If the screen indicates OUT OF CONDITION, go to step 3 and recheck.

6. Turn the ignition switch OFF.
7. Replace the secondary HO2S (Sensor 2).
8. Turn the ignition switch ON (II).
9. Reset the ECM/PCM with the HDS.
10. Do the ECM/PCM idle learn procedure.
11. Start the engine, and let it idle without load (in Park or neutral) until the radiator fan comes on.
12. Test-drive under these conditions:
- ECT SENSOR 1 above 158 °F (70 °C)
- Vehicle speed at 35 mph (56 km/h) or more for at least 23 seconds

13. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P2270 or P2271 indicated?

YES - If DTC P2270 or P2271 is indicated, check for poor connections or loose terminals at the secondary HO2S (Sensor 2) and the ECM/PCM, then go to step 1.

NO - If Temporary DTC or DTC P2270 or P2271 is not indicated, or if any other Temporary DTCs or DTCs are indicated, 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 - If there was no Temporary DTCs or DTCs indicated on step 13, troubleshooting is complete. If any other Temporary DTCs or DTCs was indicated on step 13, go to the indicated DTC's troubleshooting.

NO - If the screen indicates FAILED, check for poor connections or loose terminals at the secondary HO2S (Sensor 2) and the ECM/PCM, then go to step 1. If the screen indicates EXECUTING, keep driving until a result comes on. If the screen indicates OUT OF CONDITION, go to step 11 and recheck.