DTC Troubleshooting

DTC Troubleshooting: P2123

DTC P2123: APP Sensor A (TP Sensor D) 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

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

2. Check APP SENSOR A in the DATA LIST with the HDS.

Is there about 4.85 V or more?
YES - Go to step 3.

NO - Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the APP sensor and the ECM.


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

4. Disconnect the APP sensor 6P connector.

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

6. Measure the voltage between APP sensor 6P connector terminals No. 5 and No. 6.

Is there about 5 V?
YES - Go to step 8.

NO - Go to step 7.






7. Measure the voltage between ECM connector terminals A20 and A23.

Is there about 5 V?
YES - Repair open in the wire between the ECM (A23) and the APP sensor, then go to step 10.

NO - Go to step 15.






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

9. Replace the APP sensor. Service and Repair

10. Reconnect all connectors.

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

12. Reset the ECM with the HDS.

13. Do the ECM idle learn procedure. ECM Idle Learn Procedure

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

Is DTC P2123 indicated?
YES - Check for poor connections or loose terminals at the APP sensor and the ECM, then go to step 1.

NO - Troubleshooting is complete. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.


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

16. Reconnect all connectors.

17. Update the ECM if it does not have the latest software, ECM Update or substitute a known-good ECM. Initial Inspection and Diagnostic Overview

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

Is DTC P2123 indicated?
YES - Check for poor connections or loose terminals at the APP sensor and the ECM. If the ECM was updated, substitute a known-good ECM, Initial Inspection and Diagnostic Overview then recheck. If the ECM was substituted, go to step 1.

NO - If the ECM was updated, troubleshooting is complete. If the ECM was substituted, replace the original ECM. Service and Repair If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.