Engine Temperature Sensor: Description and Operation

The Coolant Temperature Sensor is a thermistor which relays an engine coolant temperature signal to the ECM. Temperature changes cause resistance through the sensor to vary, thus creating a signal the ECM can interpret. This signal is used as one of the criteria to determine when the system is ready to enter closed loop mode and is also factored into many other ECM control functions.

Coolant Temp.(°C/°F) Resistance (K ohms)

-10 / 14 7 - 12
10 / 50 3 - 5
20 / 68 2 - 3
50 / 122 0.7 - 1
80 / 176 0.2 - 0.4