Coolant Temperature Sensor/Switch (For Computer): Testing and Inspection

ENGINE COOLANT TEMPERATURE (ECT) SENSOR
The engine coolant temperature sensor installed in the engine coolant passage of the cylinder head detects the engine coolant temperature and emits signals to the PCM. This part employs a thermistor which is sensitive to changes in temperature. The electric resistance of the thermistor decreases in response to a temperature rise (NTC). The PCM determines engine coolant temperature by the sensor output voltage and provides optimum fuel enrichment when the engine is cold.

Circuit Diagram:

Using Hi-Scan (PRO):

SENSOR CHECKING

USING MULTI-METER
1. Remove the engine coolant temperature sensor from the intake manifold.




2. With the temperature sensing portion of the engine coolant temperature sensor immersed in hot engine coolant, check the resistance.




3. If the resistance deviates from the standard value greatly, replace the sensor.

HARNESS INSPECTION PROCEDURES
Refer to "P0117, P0118" DTC inspection procedures.

Troubleshooting Procedures:

TROUBLESHOOTING HINTS
If the fast idle speed is not adequate or the engine gives off dark smoke during warm-up, the engine coolant temperature sensor might be the cause.

INSTALLATION
1. Apply sealant LOCTITE 962T or the equivalent to the threaded portion.
2. Install the engine coolant temperature sensor and tighten it to the specified torque.

Tightening torque
Engine coolant temperature sensor:
20-40 Nm (200-400 kg-cm, 14-29 lb-ft)

3. Securely connect the harness connector.