Mass Airflow (MAF) Sensor

MAF sensor uses a hot film type sensing element. Hot wire/film is heated to a precalibrated temperature by ECM. Incoming air passing through MAF sensor causes hot wire/film to cool, resulting in the need for ECM to apply additional current to maintain precalibrated temperature. ECM measures airflow by monitoring change in required current supplied to hot wire/film.

If MAF sensor output current is outside of normal operational range, ECM senses a MAF sensor malfunction. ECM will then take driving condition information from throttle position sensor. During this period, ECM limits engine speed to less than 2000 RPM. This alerts driver vehicle is operating under fail-safe conditions and needs attention.