Air Flow Meter/Sensor: Description and Operation

GF07.07-P-6000AMG Component Description For a Hot Film Mass Air Flow Sensor







The hot film mass air flow sensors located at the outlet of the respective air filter housing cover.

Task
The hot film mass air flow sensors (HFM) detect the air mass fed to the engine.

Design
The hot film mass air flow sensors consist of a temperature regulated resistor and a plastic housing with integrated electronics and a 4-pin plug connector.

Function
The integral electronics in the hot film MAF sensor controls the nominal temperature (of about 160 °C) of the heating resistor. The temperature of the heating resistor is detected via a sensor resistor. If a temperature change occurs as a result of an increased or reduced air flow, the electronics correct the voltage at the heating resistor until the specified temperature is achieved again. This regulating current is evaluated by the hot film MAF sensor and converted into a sensor signal.

The information about air mass is transmitted in the form of frequency and cycle duration of the sensor signal to the ME control unit (N3/10).







Using STAR DIAGNOSIS, the cycle duration of the sensor signal can be read out.

The intake air temperature of the hot film mass air flow sensor is also detected but not evaluated by the ME control unit. The signal from the intake air temperature sensor (B17) is used for the intake air temperature.