Hot-Film Mass Airflow Sensor

The hot-film mass airflow sensor senses mass of intake air. Sensor is located in air intake channel between throttle body and air cleaner. The hot-film mass airflow sensor uses an adjustable voltage level to control temperature of a heating resistor. The temperature of the heating resistor is measured by a sensing resistor.

The heating resistor is kept at 320°F (160°C) more than intake air temperature. If intake air temperature changes due to increased or decreased airflow, the adjustable voltage is changed to maintain the 320°F (160°C) difference. The changing adjustable voltage is used by the Engine Control Module (ECM) to measure intake air mass.