Mass Airflow Sensor

A hot-wire air mass sensor is used to measure airflow into the engine. The sensor is attached to air filter housing. The hot-wire in sensor is kept at 356°F (180°C) above air temperature.

As airflow increases, the wire is cooled and the resistance of the sensor changes. The resulting current change is converted to a voltage signal and is used by the ECM to calculate the volume of air taken in.

If a fault develops with mass airflow sensor signal, the signal from throttle valve potentiometer is used as a substitute in order for the car to be driveable.