DTC Troubleshooting

DTC Troubleshooting: P0125 (86)

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 10 °F (-12 °C) or less indicated?

YES -

Check for poor connections or loose terminals at ECT sensor 1, ECT sensor 2, and the PCM. If the connections and the terminals are OK, replace ECT sensor 1, then go to step 7.

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. Start the engine, and let it idle until ECT SENSOR 1 goes up to about 158 °F (70 °C).

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

YES -

Go to step 6.

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 PCM.

6. Check the thermostat Testing and Inspection.

Is the thermostat OK?

YES -

Check for poor connections or loose terminals at ECT sensor 1, ECT sensor 2, and the PCM. If the connections and the terminals are OK, replace ECT sensor 1 ECT Sensor 1 Replacement, then go to step 7.

NO -

Replace the thermostat Service and Repair, then go to step 7.

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

8. Reset the PCM with the HDS.

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

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

11. Start the engine, and let it idle until ECT SENSOR 1 goes up to about 158 °F (70 °C).

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

YES -

Go to step 1 and recheck.

NO -

Troubleshooting is complete.