DTC Troubleshooting
DTC Troubleshooting: P2251, P2254, 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 Initial Inspection and Diagnostic Overview.
- 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), or press the engine start/stop button to select the ON mode.
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 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 ECM/PCM.
5. Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.
6. Jump the SCS line with the HDS.
7. Disconnect the A/F sensor (Sensor 1) 6P connector.
8. Disconnect ECM/PCM connector B (49P).
9. Check for continuity between A/F sensor (Sensor 1) 6P connector terminal No. 4 and ECM/PCM connector terminal B13 (B14)*.
Is there continuity?
YES -
Go to step 10.
NO -
Repair open in the wire between the ECM/PCM(B13 (B14)*) and the A/F sensor (Sensor 1), then go to step 14.
10. Reconnect ECM/PCM connector B (49P).
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, then let it idle for 2 minutes.
12. Measure the voltage between A/F sensor (Sensor 1) 6P connector terminal No. 4 and body ground.
Is there about 0.2 V or less?
YES -
Go to step 20.
NO -
Go to step 13.
13. Replace the A/F sensor (Sensor 1) A/F Sensor Replacement.
14. Reconnect all connectors.
15. Turn the ignition switch to ON (II), or press the engine start/stop button to select the ON mode.
16. Reset the ECM/PCM with the HDS.
17. Do the ECM/PCM idle learn procedure ECM/PCM Idle Learn Procedure.
18. 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 ECM/PCM, then go to step 1.
NO -
Go to step 19.
19. 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 18, 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 ECM/PCM, then go to step 1. If the screen indicates NOT COMPLETED, keep idling until a result comes on.
20. Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.
21. Reconnect all connectors.
22. Update the ECM/PCM if it does not have the latest software ECM/PCM Update, or substitute a known-good ECM/PCM.
23. Start the engine, and let it idle.
24. 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 ECM/PCM. If the ECM/PCM was updated, substitute a known-good ECM/PCM, then go to step 23. If the ECM/PCM was substituted, go to step 1.
NO -
Go to step 25.
25. 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 ECM/PCM was updated, troubleshooting is complete. If the ECM/PCM was substituted, replace the original ECM/PCM Service and Repair. If any other Pending or Confirmed DTCs were indicated in step 24, 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 ECM/PCM. If the ECM/PCM was updated, substitute a known-good ECM/PCM, then go to step 23. If the ECM/PCM was substituted, go to step 1. If the screen indicates NOT COMPLETED, keep idling until a result comes on.