Air Flow Meter/Sensor: Description and Operation

The air flow meter measures intake air flow rate by measuring a part of the entire flow. Measurements are made such a way that the ECU receives electrical output signals varied by amount of heat emitting from the hot film placed in the stream of intake air. When intake air flows into the intake manifold through a route around the hot film, the heat generated from the hot film is taken away by air. The amount of heat reduction depends on air flow. The temperature of hot film is automatically controlled to a certain number of degrees. It is necessary to supply hot film with more electric current in order to maintain the temperature of the hot film. The ECU detects air flow by means of the current change.