Circuit Description

Mass Airflow (MAF) sensor is an airflow meter that measures amount of air entering engine. PCM uses MAF sensor signal in order to provide correct fuel delivery for a wide range of engine speeds and loads. A small quantity of air entering engine indicates a deceleration or idle. A large quantity of air entering engine indicates an acceleration or high load condition.

PCM applies voltage to sensor on signal circuit. Sensor uses the voltage in order to produce a frequency based on inlet airflow through the sensor bore. The frequency varies within a range of around 2000 Hertz at idle to about 10,000 Hertz at maximum engine load. PCM uses inputs from the MAP, IAT and engine speed in order to calculate a predicted MAF value.

PCM compares actual MAF sensor frequency signal to predicted MAF value. This comparison will determine if signal is stuck based on a lack of variation or is too low or too high for a given operating condition. DTC will set if actual MAF sensor frequency signal is not within a predetermined range of calculated MAF value.