Glossary Term
Hot Wire MAF Sensor
The most common type of mass air flow sensor in use today. It uses a thin platinum or tungsten wire that is electrically heated to a specific temperature above the ambient air temperature. As air flows past the wire, it cools it down, changing its electrical resistance. The ECU measures the current needed to maintain the wire's constant temperature and translates this into an air mass flow reading.
Hot Wire MAF sensor internals: the heated platinum/tungsten wire (center) and intake air temperature sensor (left, red bead). Air flowing past the wire cools it, and the ECU measures the current required to maintain constant temperature.
Hot Wire MAF sensor installed in a Saab — the sensing element is visible through the housing window.