Engine - Coolant Temperature Sensor/Switch: Description and Operation

Coolant temperature sensor (R50)
Coolant temperature sensor

Function
The sensor is an NTK with a negative temperature coefficient; it is located in the coolant system. The sensor monitors the engine-coolant temperature and is linked to the engine control module by two leads. The signal is used to control the injection duration depending on the engine temperature. The value determined is also used to control the radiator fan speed and to display the coolant temperature in the instrument cluster.

Installation location
The sensor is located to the side above the transmission on the engine block.

Failure
In the event an engine coolant temperature sensor failure, a fault code is entered in the engine control module and a substitute value is used. The vehicle handling is negatively influenced by the substitute value in all driving states.