The Air Flow Sensor (MAF) is located in the intake air stream and measures the mass of air entering the engine. The hot wire component of the MAF cools when air mass flows past. The electronic circuit component measures this change in temperature and converts it to a voltage or frequency signal. This signal is sent to the engine control unit to determine how much fuel to deliver to the engine so the vehicle can maintain optimal performance. Hitachi Automotive Systems Americas, Inc.’s MAF accurately controls the engine’s air/fuel ratio for improved fuel economy and reduced emissions.