Toyota Corolla (E120): Circuit description

Refer to dtc p0115

Dtc no.

Dtc detection condition

Trouble area

P0125 If the engine coolant temperature (ect) was less than –6.6 °C (20 °F) when starting the engine, and 20 minutes after the engine start, the ect sensor still indicates below 20 °C (68 °F)
  • Cooling system
  • engine coolant temperature sensor
  • thermostat
If the ect was between –6.6 °C (20 °F) and 10 °C (50 °F) when start, 5 minutes after the start, the ect sensor still indicates below 20 °C (68 °F)
If the ect was greater than 10 °C (50 °F) when starting the engine, and 2 minutes after the engine start, ect sensor still indicates below 20 °C (68 °F)

Monitor description

The engine coolant temperature (ect) sensor is used to monitor the temperature of the engine coolant. The resistance of the sensor varies with the actual coolant temperature. The ecm applies a voltage to the sensor and the varying resistance of the sensor causes the signal voltage to vary. The ecm monitors the ect signal voltage after engine start–up. If, after sufficient time has passed, the sensor still reports that the engine is not warm enough for closed–loop fuel control, the ecm interprets this as a fault in the sensor or cooling system.

Example: the engine coolant temperature was 0 c (32 f) at engine start. After 5 minutes running time, the coolant temperature sensor still indicates that the engine is not warm enough to begin air–fuel ratio feedback control.

The ecm interprets this as a fault in the sensor or cooling system and will set a dtc.

Monitor strategy

Typical enabling conditions

Typical enabling conditions

Typical malfunction thresholds

Typical malfunction thresholds

Wiring diagram

Wiring diagram

Refer to dtc p0115

    Share this page:

    Other materials:

    Check mode procedure
    1. Dtc check (check mode) Hint: hand–held tester only: compared to the normal mode, the check mode has more sensing ability to detect malfunctions. Furthermore, the same diagnostic items which are detected in the normal mode can also be detected in the check mode. Procedure for check m ...

    Turning on the high beam headlights
    1 With the headlights on, push the lever away from you to turn on the high beams. Pull the lever toward you to the center position to turn the high beams off. 2 Pull the lever toward you and release it to flash the high beams once. You can flash the high beams with the headlights on or off. &# ...

    Cd sound skips
    Inspection procedure 1 Disc cleaning Disk cleaning ) if the disk gets dirty, clean the disk by wiping the surface from the center to outside in the radial directions with a soft cloth. Notice: do not use a conventional record cleaner or anti–static preservative. Standard: ...