DTC Troubleshooting

DTC P0125: ECT Sensor 1 malfunction/Slow Response ('06-08 models)

NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information.

1. Start the engine, and let it idle 5 minutes or more.
2. Check ECT SENSOR 1 in the DATA LIST with the HDS.

Is about 0 °F (-18 °C) or less indicated?

YES - Go to step 9.

NO - Go to step 3.

3. Allow the engine to cool to 104 °F (40 °C) or less.
4. Note the value of ECT SENSOR 1 and ECT SENSOR 2 in the DATA LIST with the HDS.
5. Start the engine, and let it idle.
6. Let the engine idle until ECT SENSOR 1 goes up 40 °F (22 °C) or more from the recorded temperature.
7. Note the value of ECT SENSOR 2 in the DATA LIST with the HDS.
8. Compare ECT SENSOR 2 and the recorded temperature.

Did ECT SENSOR 2 change 14 °F (8 °C) or more?

YES - Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at ECT sensor 1, ECT sensor 2, and the ECM/PCM.

NO - Check the thermostat. If the thermostat is OK, go to step 9. If the thermostat is faulty, replace it, then go to step 11.

9. Turn the ignition switch OFF.
10. Replace ECT sensor 1.
11. Turn the ignition switch ON (II).
12. Reset the ECM/PCM with the HDS.
13. Do the ECM/PCM idle learn procedure.
14. Allow the engine to cool to ambient temperature.
15. Start the engine, and let it idle for 20 minutes.
16. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P0125 indicated?

YES - Check for poor connections or loose terminals at ECT sensor 1, ECT sensor 2, and the ECM/PCM, then go to step 1.

NO - Go to step 17.

17. Monitor the OBD STATUS for DTC P0125 in the DTCs MENU with the HDS.

Does the screen indicate PASSED?

YES - Troubleshooting is complete. If any other Temporary DTCs or DTCs were indicated in step 16, go to the indicated DTC's troubleshooting.

NO - If the screen indicates FAILED, check for poor connections or loose terminals at ECT sensor 1, ECT sensor 2, and the ECM/PCM, then go to step 1. If the screen indicates NOT COMPLETED, go to step 14.