Coolant Temperature Sensor Operation

The coolant temperature sensor is located in the cylinder head. This sensor provides ECU with an engine temperature signal. If signal from temperature sensor is not reaching ECU, an engine temperature of 86°F (30°C) will be assumed by ECU.

If sensor reads a high engine temperature (with cooling system operating properly), this would indicate combustion temperature that is too high. The control unit would then richen the mixture (to the point allowed by the oxygen sensor and air mass meter signals) to lower combustion and engine temperature.