( TF09EACK72100090125FAAT00 )
DTC Troubleshooting: P0125 (86)
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.
  1. Start the engine, and let it idle for 5 minutes or more.
  1. Check the ECT SENSOR 1 in the DATA LIST with the HDS.
Is about −18 °C (0 °F) 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.
NO -
Go to Step 3 .
  1. Turn the ignition switch to LOCK (0).
  1. Allow the engine to cool 40 °C (104 °F) or less.
  1. Make sure the temperature difference of ECT SENSOR 1 and ECT SENSOR 2 is between about 10 °C (50 °F) in the DATA LIST with the HDS.
  1. Start the engine, and let it idle until ECT sensor 1goes up around 70 °C (158 °F).
Dose ECT sensor 2 also show about 70 °C (158 °F)?
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.■
Is the thermostat OK?
YES -
Check for poor connection or loose terminals at ECT SENSOR1, ECT SENSOR 2, and the ECM/PCM. If they are OK, replace ECT SENSOR 1, then go to Step 8 .
NO -
  1. Turn the ignition switch to LOCK (0).
  1. Allow the engine to cool 40 °C (104 °F) or less.
  1. Check the temperature difference of ECT SENSOR 1 and ECT SENSOR 2 is between about 10 °C (50 °F) in the DATA LIST with the HDS.
  1. Start the engine, and let it idle until ECT sensor 1goes up around 70 °C (158 °F).
Dose ECT sensor 2 also show about 70 °C (158 °F)?
YES -
Go to Step 1 and recheck.
NO -
Troubleshooting is complete.■