Nissan Maxima Service and Repair Manual: 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>

*: These data are reference values and are measured between ECM terminals 46 (Engine coolant temperature sensor) and 52 (Sensor ground).

DTC Logic

DTC DETECTION LOGIC

NOTE:

•  If DTC P0125 is displayed with P0116, first perform the trouble diagnosis for DTC P0116. Refer to EC- 201, "DTC Logic".
•  If DTC P0125 is displayed with P0117 or P0118, first perform the trouble diagnosis for DTC P0117, P0118. Refer to EC-204, "DTC Logic".

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.

2.CHECK ENGINE COOLANT TEMPERATURE SENSOR FUNCTION

With CONSULT

1. Turn ignition switch ON.
2. Select "DATA MONITOR" mode with CONSULT.
3. Check that "COOLAN TEMP/S" is above 10C (50F).

With GST

Follow the procedure "With CONSULT" above.

3.PERFORM DTC CONFIRMATION PROCEDURE

With CONSULT

1. Start engine and run it for 65 minutes at idle speed.

   If "COOLAN TEMP/S" increases to more than 10C (50F) within 65 minutes, stop engine because the test result will be OK. CAUTION: Never overheat engine.

2. Check 1st trip DTC.

With GST

Follow the procedure "With CONSULT" above.

Diagnosis Procedure

1.CHECK GROUND CONNECTION

1. Turn ignition switch OFF.
2. Check ground connection E9.

2.CHECK ENGINE COOLANT TEMPERATURE SENSOR

3.CHECK THERMOSTAT OPERATION

When the engine is cold [lower than 70C (158F)] condition, grasp lower radiator hose and confirm that the engine coolant does not flow.

4.CHECK INTERMITTENT INCIDENT

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 as per the following.