DTC P0125: ECT Sensor 1 Malfunction/Slow Response
- Start the engine, and let it idle for 5 minutes or more.
- Check ECT SENSOR 1 in the DATA LIST with the HDS.
Is about 64°F (-18°C) or less, or 4.45 V or more indicated?
YES - Go to step 9.
NO - Go to step 3.
- Allow the engine to cool to 104°F (40°C) or less.
- Note the value of ECT SENSOR 1 and ECT SENSOR 2 in the DATA LIST with the HDS.
- Start the engine, and let it idle.
- Let the engine idle until ECT SENSOR 1 goes up 68°F (20°C) or more from the recorded temperature.
- Note the value of ECT SENSOR 2 in the DATA LIST with the HDS.
- 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 (see THERMOSTAT TEST ). If the thermostat is OK, go to step 9. If you had to replace the thermostat, go to step 11.
- Turn the ignition switch OFF.
- Replace ECT sensor 1 (see ECT SENSOR 1 REPLACEMENT ).
- Turn the ignition switch ON (II).
- Reset the ECM/PCM with the HDS.
- Do the ECM/PCM idle learn procedure (see ECM/PCM IDLE LEARN PROCEDURE ).
- Allow the engine to cool to ambient temperature.
- Start the engine, and let it idle for 20 minutes.
- 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.
- 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 DTCs 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.