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 they are OK, replace ECT SENSOR 1 ECT Sensor 1 Replacement.
NO -
Go to step 3.
3. Turn the ignition switch to LOCK (0).
4. Allow the engine to cool 104 °F (40 °C) or less.
5. Start the engine, and let it idle until ECT SENSOR 1 goes up 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 ECM/PCM.�
6. 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 they are OK, replace ECT sensor 1 ECT Sensor 1 Replacement, then go to step 9.
NO -
Replace the thermostat Thermostat Replacement, then go to step 7.
7. Turn the ignition switch to ON (II).
8. Reset the ECM/PCM with the HDS.
9. Turn the ignition switch to LOCK (0).
10. Allow the engine to cool 104 °F (40 °C) or less.
11. Start the engine, and let it idle until ECT SENSOR 1 goes up around 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.�