Air Flow Meter/Sensor: Description and Operation

MASS AIR FLOW (MAF) SENSOR




The mass air flow (MAF) sensor is of the thermal control type. The MAF sensor consists of a heat resistor element located inside the bore of the throttle body, an air straightening screen (2), and a control circuit board (1). The heat resistor is cooled off by the air entering the MAF sensor. The control circuit maintains the heat resistor temperature within a predetermined range. When the amount of air entering the sensor increases, the signal created by the sensor and sent to the powertrain control module (PCM), also increases. When the air flow decreases, so does the signal current to the PCM. The MAF sensor is an integral part of the throttle body.

The mass air flow (MAF) sensor measures the amount of air which passes over the heat resistor in a given amount of time. The PCM uses this information in order to determine the operating requirements of the engine and control fuel delivery. A large quantity of air movement indicates acceleration, while a small quantity indicates deceleration or idle.