DTC Troubleshooting

DTC Troubleshooting: P0125, P0125

DTC P0125:

ECT Sensor 1 Malfunction/Slow Response

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. Start the engine, and let it idle for 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 -

Check for poor connection or loose terminals at ECT SENSOR 1, ECT SENSOR 2, and the ECM/PCM. If the connections and the terminals are OK,replace ECT SENSOR 1 ECT Sensor 1 Replacement,then go to step 8.

NO -

Go to step 3.

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

4. Allow the engine to cool to 104 °F (40 °C) or less.

5. Make sure the difference between ECT SENSOR 1 and ECT SENSOR 2 is less than about 50 °F (10 °C) in the DATA LIST with the HDS.

6. Start the engine, and let it idle until ECT sensor 1 reads about 158 °F (70 °C)

Does the ECT sensor 2 also show about 158 °F (70 °C)?

YES -

Go to step 7.

NO -

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.�

7. Check the thermostat Testing and Inspection.

Is the thermostat OK?

YES -

Check for poor connection or loose terminals at ECT sensor 1, ECT sensor 2, and the ECM/PCM. If the connections and the terminals are OK, replace ECT SENSOR 1 ECT Sensor 1 Replacement, then go to step 8.

NO -

Replace the thermostat Thermostat Replacement, then go to step 8.

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

9. Reset the ECM/PCM with the HDS.

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

11. Allow the engine to cool to 104 °F (40 °C) or less.

12. Make sure the temperature difference between ECT SENSOR 1 and ECT SENSOR 2 is about 50 °F(10 °C) in the DATA LIST with the HDS.

13. Start the engine, and let it idle until ECT sensor 1 reads about 158 °F (70 °C)

Does the ECT sensor 2 also read about 158 °F(70 °C)?

YES -

Go to step 1 and recheck.

NO -

Troubleshooting is complete.�