Coolant temperature sensor component description - GF07.04-P-6040V

ENGINE 273.961 in MODEL 216, 221 up to Model Year 8

Fig 1: Identifying Coolant Temperature Sensor

Courtesy of MERCEDES-BENZ USA

Location

The coolant temperature sensor is located at the rear in the left cylinder head.

Task

Detects the coolant temperature and supplies a voltage signal to the ME control unit.

Function

The NTC resistor integrated in the coolant temperature sensor, alters its electrical resistance in line with the coolant temperature.

NTC is the abbreviation for "N egative T emperature C oefficient", which means electrical resistance falls as the temperature increases (hot conductor).

Example:

Coolant temperature	Resistor	Voltage signal
20°C	3090 Ω ±5%	3.39 V
80°C	320 Ω ±5%	0.89 V

Body

Metal casing with an integrated, highly responsive NTC resistor and a 2-pole, slanted plug connection. It is inserted into a bore hole and sealed with an O-ring. Fixing via a bracket.

The rapidly responsive NTC temperature sensor is supplied with 5 V by the ME control unit via a series resistor (1470 Ω ±1 %). Following a short-circuit to battery voltage or 5 V (without a series resistor), the temperature sensor coolant is defective.

The signal is plausible between 0.1 V to 4.93 V, otherwise a fault is identified and a substitute value taken by the ME control unit from a stored temperature model.