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

Coolant Temperature Sensor:

The Coolant Temperature Sensor installed in the engine coolant passage of the intake manifold, is a resistor-based sensor. The ECU judges engine temperature by the resistance change in the sensor. As the coolant temperature rises, the sensor resistance is lowered. With this input the ECU can control fuel mixture and determine if the engine is in closed or open loop.