Component description for the hot film MAF sensor - GF07.07-P-6000KE

ENGINE 271.921 /940 /941 /944 /946 /948 /955 /956

Arrangement

The hot film MAF sensor is located directly at the outlet of the air filter housing.

Fig 1: Locating Hot Film MAF Sensor - Engine 271.921 /940 /941 /944 /946 /948 /955 /956

Task

The hot film MAF sensor (HFM) detects the air mass sent to the engine and sends an appropriate voltage signal to the ME control unit (N3/10).

Design

Fig 2: Identifying Hot Film MAF Sensor Components - Engine 271.921 /940 /941 /944 /946 /948 /955 /956

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 voltage.

The sensor voltage is used by the ME control unit as a measure for the applied air mass.