P0125

P0125 ECT SENSOR





Description





The engine coolant temperature sensor is used to detect the engine coolant temperature. The sensor modifies a voltage signal from the ECM. The modified signal returns to the ECM as the engine coolant temperature input. The sensor uses a thermistor which is sensitive to the change in temperature. The electrical resistance of the thermistor decreases as temperature increases.





[Reference data]





CAUTION: Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in damage to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.




DTC Logic

DTC DETECTION LOGIC

NOTE:
- If DTC P0125 is displayed with P0117 or P0118, first perform the trouble diagnosis for DTC P0117 or
P0118. P0117.
- If DTC P0125 is displayed with P0116, first perform the trouble diagnosis for DTC P0116. P0116.






DTC CONFIRMATION PROCEDURE
1.PRECONDITIONING
If DTC Confirmation Procedure has been previously conducted, always perform the following before conducting the next test.
1. Turn ignition switch OFF and wait at least 10 seconds.
2. Turn ignition switch ON.
3. Turn ignition switch OFF and wait at least 10 seconds.
- GO TO 2.
2.CHECK ENGINE COOLANT TEMPERATURE SENSOR FUNCTION
With CONSULT-III
1. Turn ignition switch ON.
2. Select "DATA MONITOR" mode with CONSULT-III.
3. Check that "COOLANT TEMP/S" is above 5�C (41�F).
With GST
Follow the procedure "With CONSULT-III" above.
Is it above 5�C (41�F)?
YES - INSPECTION END
NO - GO TO 3.
3.PERFORM DTC CONFIRMATION PROCEDURE
With CONSULT-III
1. Activate "INSPECTION MODE 1" ( Mode 1) to start engine, and run engine for 65 minutes at idle speed.
2. Check 1st trip DTC.
If "COOLANT TEMP/S" increases to more than 5�C (41�F) within 65 minutes, turn ignition switch OFF because the test result will be OK.

CAUTION:
Be careful not to overheat engine.
With GST
Follow the procedure "With CONSULT-III" above.
Is 1st trip DTC detected?
YES - P0125
NO - INSPECTION END




Diagnosis Procedure
1.CHECK GROUND CONNECTION
1. Turn ignition switch OFF.
2. Check ground connection E9. Refer to Ground Inspection in Circuit Inspection.
Is the inspection result normal?
YES - GO TO 2.
NO - Repair or replace ground connection.
2.CHECK ENGINE COOLANT TEMPERATURE SENSOR
P0125.
Is the inspection result normal?
YES - GO TO 3.
NO - Replace engine coolant temperature sensor.
3.CHECK THERMOSTAT OPERATION
When the engine is cold [lower than 70�C (158�F)] condition, grasp lower radiator hose and confirm the engine coolant does not flow.
Is the inspection result normal?
YES - GO TO 4.
NO - Repair or replace thermostat. Service and Repair.
4.CHECK INTERMITTENT INCIDENT
Intermittent Incident.
- INSPECTION END




Component Inspection
1.CHECK ENGINE COOLANT TEMPERATURE SENSOR
1. Turn ignition switch OFF.
2. Disconnect engine coolant temperature sensor harness connector.
3. Remove engine coolant temperature sensor.





4. Check resistance between engine coolant temperature sensor terminals by heating with hot water as shown in the figure.





Is the inspection result normal?
YES - INSPECTION END
NO - Replace engine coolant temperature sensor.