DTC Troubleshooting

DTC Troubleshooting: P0123

DTC P0123: TP Sensor A 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. Clear the DTC with the HDS.

3. Check TP SENSOR A in the DATA LIST with the HDS.

Is there about 4.8 V or more?
YES - Go to step 4.

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


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

Are DTC P0123 and P0223 indicated at the same time?
YES - Go to step 13.

NO - Go to step 5.


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

6. Disconnect the throttle body 6P connector.

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

8. Measure the voltage between throttle body 6P connector terminal No. 1 and body ground.

Is there about 5 V?
YES - Go to step 18.

NO - Go to step 9.






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

10. Jump the SCS line with the HDS.

11. Disconnect ECM connector C (44P).

12. Check for continuity between ECM connector terminal C20 and throttle body 6P connector terminal No. 1.

Is there continuity?
YES - Go to step 25.

NO - Repair open in the wire between the throttle body and the ECM (C20), then go to step 20.






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

14. Disconnect the throttle body 6P connector.

15. Jump the SCS line with the HDS.

16. Disconnect ECM connector C (44P).

17. Check for continuity between ECM connector terminal C39 and throttle body 6P connector terminal No. 4.

Is there continuity?
YES - Go to step 25.

NO - Repair open in the wire between the throttle body and the ECM (C39), then go to step 20.






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

19. Replace the throttle body. Removal and Replacement

20. Reconnect all connectors.

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

22. Reset the ECM with the HDS.

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

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

Is DTC P0123 indicated?
YES - Check for poor connections or loose terminals at the throttle body 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.


25. Reconnect all connectors.

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

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

Is DTC P0123 indicated?
YES - Check for poor connections or loose terminals at the throttle body 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.