DTC Troubleshooting

DTC Troubleshooting: P2251, P2254

DTC P2251: Rear A/F Sensor (Bank 1, Sensor 1) VS Circuit High Voltage

DTC P2254: Front A/F Sensor (Bank 2, Sensor 1) VS Circuit High Voltage

NOTE:

- Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information. Reading and Clearing Diagnostic Trouble Codes

- If DTC P2251 and/or P2254* is stored at the same time as DTC P0134 and/or P0154*, troubleshoot DTC P2251 and/or P2254* first, then recheck for P0134 and/or P0154*.

- Information marked with an asterisk (*) applies to the front bank (Bank 2).

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 for 2 minutes.

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

Is DTC P2251 and/or P2254* indicated?
YES - Go to step 5.

NO - Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the A/F sensor (Sensor 1) and the PCM.


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

6. Jump the SCS line with the HDS.

7. Disconnect the A/F sensor (Sensor 1) 6P connector.

8. Disconnect PCM connector B (24P).

9. Connect A/F sensor (Sensor 1) 6P connector terminal No. 4 to body ground with a jumper wire.






10. Check for continuity between PCM connector terminal B12 (B20)* and body ground.

Is there continuity?
YES - Go to step 11.

NO - Repair open in the wire between the PCM (B12 (B20)*) and the A/F sensor (Sensor 1), then go to step 16.






11. Remove the jumper wire from the A/F sensor (Sensor 1) 6P connector, then reconnect PCM connector B (24P).

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

13. Measure the voltage between PCM connector terminals B12 (B20)* and C12.

Is there about 0.2 V or less?
YES - Go to step 22.

NO - Go to step 14.






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

15. Replace the A/F sensor. A/F Sensor Replacement

16. Reconnect all connectors.

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

18. Reset the PCM with the HDS.

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

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

Is DTC P2251 and/or P2254* indicated?
YES - Check for poor connections or loose terminals at the A/F sensor (Sensor 1) and the PCM, then go to step 1.

NO - Go to step 21.


21. Monitor the OBD STATUS for DTC P2251 and/or P2254* 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 20, go to the indicated DTC's troubleshooting.

NO - If the screen indicates FAILED, check for poor connections or loose terminals at the A/F sensor (Sensor 1) and the PCM, then go to step 1. If the screen indicates NOT COMPLETED, keep idling until a result comes on.


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

23. Reconnect all connectors.

24. Update the PCM if it does not have the latest software, PCM Update or substitute a known-good PCM. Reading and Clearing Diagnostic Trouble Codes

25. Start the engine, and let it idle.

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

If DTC P2251 and/or P2254* indicated?
YES - Check for poor connections or loose terminals at the A/F sensor (Sensor 1) and the PCM. If the PCM was updated, substitute a known-good PCM, Reading and Clearing Diagnostic Trouble Codes then recheck. If the PCM was substituted, go to step 1.

NO - Go to step 27.


27. Monitor the OBD STATUS for DTC P2251 and/or P2254* in the DTCs MENU with the HDS.

Does the screen indicate PASSED?
YES - If the PCM was updated, troubleshooting is complete. If the PCM was substituted, replace the original PCM. Service and Repair If any other Pending or Confirmed DTCs were indicated in step 26, go to the indicated DTC's troubleshooting.

NO - If the screen indicates FAILED, check for poor connections or loose terminals at the A/F sensor (Sensor 1) and the PCM. If the PCM was updated, substitute a known-good PCM, Reading and Clearing Diagnostic Trouble Codes then go to step 25. If the PCM was substituted, go to step 1. If the screen indicates NOT COMPLETED, keep idling until a result comes on.