Automatic Transmission

The Mass Air Flow (MAF) sensor, located between air filter and throttle body, measures mass of air entering the engine due to volumetric displacement.

The MAF sensor operates on the principle that if a mass is maintained at a constant temperature above the ambient environment, then thermal loss is proportional to mass flow of the cooling medium it is subjected to. PCM heats a wire element above ambient temperature. As air passes through the sensor, the air cools the wire element. The PCM supplies more power to the wire to keep it at a constant temperature difference. When a drop in power useage occurs, the sensor sends a signal to the PCM indicating the drop. Signal increases with airflow into the engine.