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

PURPOSE
The Engine Coolant Temperature sensor provides a signal used by the Engine Control Module for ignition timing, idle speed control and fuel injection quantity.
In addition, various functions such as oxygen sensor control, deceleration fuel shut-off and evaporative emission system operations are based on output from the engine coolant temperature sensor.

OPERATION
The Engine Coolant Temperature sensor is an Negative Temperature Coefficient (NTC) resistor.
The electrical resistance of the sensor decreases as coolant temperature increases.