Engine - Coolant Temperature Sensor/Switch: Description and Operation

Water Thermosensor:

PURPOSE
Measures engine coolant temperature and signals ECU.

LOCATION
In water outlet at front of intake manifold.

OPERATION
Sensor is is a thermistor with a negative temperature coefficient. This means as temperature increases, resistance decreases. ECU measures changes in resistance and calculates engine temperature. The ECU monitors coolant temperature to calculate injector pulse width during cold start and warm-up, as well as for regulating other output functions.

TEMP. RESISTANCE (K OHMS)

-20°C (-4°F) 14.6 - 17.8
20°C (68°F) 2.2 - 2.7
40°C (104°F) 1.0 - 1.3
60°C (140°F) 0.50 - 0.65
80°C (176°F) 0.29 - 0.35