DTC Troubleshooting

DTC Troubleshooting: 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 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 -

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 Thermostat Replacement, then go to step 7.

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

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

9. 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 P0125 and recheck.

NO -

Troubleshooting is complete.�