Coolant Temperature Sensor/Switch (For Computer): Description and Operation

A thermistor built into the engine coolant temperature sensor changes the resistance value according to the engine coolant temperature.
The structure of the sensor and connection to the ECM is the same as in the intake air temp. circuit.
If the ECM detects the diagnostic trouble code P0115, it operates the fail safe function in which the engine coolant temp. is assumed to be 8O°C (176°F).