Engine Temperature Sensor: Description and Operation

Engine Coolant Temperature Sensor:

PURPOSE
Supplies the ECM with engine temperature information.

LOCATION
In the front of the intake manifold.

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. Low temperature produces high resistance (100K ohms at -40° C / -40° F) while high temperature produces low resistance (70 ohms at 130° C / 266° F).

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.