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: Coolant Temperature Sensor And Two Pin Plug Connection

Courtesy of BMW OF NORTH AMERICA, INC.

The resistance is temperature-dependent and varies between 21.7 kΩ and 37 Ω, which corresponds to a temperature of -55 °C to 155 °C.