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 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 (see ECT SENSOR 1 REPLACEMENT ).
NO: Go to step 3.
- Turn the ignition switch to LOCK (0).
- Allow the engine to cool to 104°F (40°C) or less.
- 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.
- Start the engine, and let it idle until ECT sensor 1 goes up to 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.
- Check the thermostat (see FAN MOTOR TEST
).
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 (see ECT SENSOR 1 REPLACEMENT ), then go to step 8.
NO: Replace the thermostat (see THERMOSTAT REPLACEMENT ), then go to step 8.
- Turn the ignition switch to ON (II).
- Reset the ECM/PCM with the HDS.
- Turn the ignition switch to LOCK (0).
- Allow the engine to cool to 104°F (40°C) or less.
- Check that the temperature difference between ECT SENSOR 1 and ECT SENSOR 2 is about 50°F (10°C) in the DATA LIST with the HDS.
- Start the engine, and let it idle until ECT sensor 1 goes up to 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.