DTC Troubleshooting

DTC Troubleshooting: P0118

DTC P0118: ECT Sensor 1 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

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

2. Check ECT SENSOR 1 in the DATA LIST with the HDS.

Is about -40 °F (-40 °C) or less, or 4.92 V or more indicated?
YES - Go to step 3.

NO - Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at ECT sensor 1 and the ECM/PCM.


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

4. Disconnect the ECT sensor 1 2P connector.

5. Connect ECT sensor 1 2P connector terminals No. 1 and No. 2 with a jumper wire.

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

7. Check ECT SENSOR 1 in the DATA LIST with the HDS.

Is about -40 °F (-40 °C) or less, or 4.92 V or more indicated?
YES - Go to step 8.

NO - Go to step 20.






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

9. Remove the jumper wire from the ECT sensor 1 2P connector.

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

11. Measure the voltage between the ECT sensor 1 2P connector terminal No. 2 and body ground.

Is there about 5 V?
YES - Go to step 12.

NO - Go to step 16.






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

13. Jump the SCS line with the HDS.

14. Disconnect ECM/PCM connector B (44P).

15. Check for continuity between ECT sensor 1 2P connector terminal No. 1 and ECM/PCM connector terminal B33.

Is there continuity?
YES - Go to step 27.

NO - Repair open in the wire between the ECM/PCM (B33) and ECT sensor 1, then go to step 22.






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

17. Jump the SCS line with the HDS.

18. Disconnect ECM/PCM connector B (44P).

19. Check for continuity between ECT sensor 1 2P connector terminal No. 2 and ECM/PCM connector terminal B23.

Is there continuity?
YES - Go to step 27.

NO - Repair open in the wire between the ECM/PCM (B23) and ECT sensor 1, then go to step 22.






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

21. Replace ECT sensor 1.

22. Reconnect all connectors.

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

24. Reset the ECM/PCM with the HDS.

25. Do the ECM/PCM idle learn procedure. ECM/PCM Idle Learn Procedure

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

Is DTC P0118 indicated?
YES - Check for poor connections or loose terminals at ECT sensor 1 and the ECM/PCM, then go to step 1.

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


27. Reconnect all connectors.

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

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

Is DTC P0118 indicated?
YES - Check for poor connections or loose terminals at ECT sensor 1 and the ECM/PCM. If the ECM/PCM was updated, substitute a known-good ECM/PCM, Reading and Clearing Diagnostic Trouble Codes then recheck. If the ECM/PCM was substituted, go to step 1.

NO - 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 are indicated, go to the indicated DTC's troubleshooting.