DTC Troubleshooting

Control System DTCs

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 How to Troubleshoot the Fuel And Emissions Systems.

1. ECT sensor 1 check:

-1. Start the engine, and let it idle for 5 minutes or more.

-2. Check the parameter(s) below with the HDS.





Do the current condition(s) match the threshold?
-YES- Check for poor connections or loose terminals at ECT sensor 1, ECT sensor 2, and the PCM. If they are OK, replace ECT sensor 1 ECT Sensor 1 Removal And Installation, then do the repair verification.
-NO- Go to step 2.

2. Problem verification:

-1. Turn the ignition switch to LOCK (0).

-2. Allow the engine to cool to 104 °F (40 °C) or less.

-3. Start the engine, and let it idle until ECT SENSOR 1 goes up to about 158 °F (70 °C).





-4. Check the parameter(s) below with the HDS.





Do the current condition(s) match the threshold?
-YES- The failure is duplicated. Go to step 3.
-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.

3. Thermostat check:

-1. Check the thermostat Thermostat Removal, Installation, And Test.

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 terminals are OK, replace ECT sensor 1 ECT Sensor 1 Removal And Installation, then do the repair verification.
-NO- Replace the thermostat Thermostat Removal, Installation, And Test, then do the repair verification.

Repair verification:

-1. Turn the ignition switch to ON (II).

-2. Reset the PCM with the HDS How to Troubleshoot the Fuel And Emissions Systems.

-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).





-6. Check the parameter(s) below with the HDS.

Do the current condition(s) match the threshold?
-YES- Check for poor connections or loose terminals at ECT sensor 1, ECT sensor 2, and the PCM, go to step 1.
-NO- Troubleshooting is complete. If the PCM was substituted, replace the original PCM Service and Repair. If any other Pending or Confirmed DTCs are indicated, go to the indicated DTC's troubleshooting.