Engine Temperature Sensor: Description and Operation

Coolant Temperature Sensor:

PURPOSE
Supplies the Engine Control Module (ECM) with engine temperature information.

LOCATION
Under the intake manifold at the front.

OPERATION
The ECM supplies a 5V signal to the sensor and measures voltage variation. By measuring this variation, the ECM measures coolant temperature. This input is a factor in calculations involving most ECM controlled systems.

At 20°C (68°F), resistance of the sensor is between 2 - 3K ohms. When the engine is warm (80°C / 176°F), resistance falls to between 200 - 400 ohms.

CONSTRUCTION
The coolant temperature sensor is a thermistor (a device whose resistance changes with temperature). Being immersed in a coolant passage allows the sensor to detect engine temperature.