Functional description

A temperature-dependent electrical resistor is used for temperature sensing. The circuit contains a voltage divider where the resistance can be measured depending on the temperature. A temperature is converted using a characteristic curve specific to the sensor. An NTC resistor (NTC) is installed in the coolant temperature sensor, whose resistance value drops when the temperature increases.

Fig 1: Identifying Coolant Temperature Sensor And Plug Connection

Courtesy of BMW OF NORTH AMERICA, INC.

The resistance changes from approx. 216 kΩ to 33 Ω depending on temperature, which corresponds to a temperature of -55 °C to 160 °C.