Mass Airflow (MAF) Sensor

The MAF sensor contains 3 Positive Temperature Coefficient (PTC) resistors. 2 PTC resistors are used to measure air flow. They are connected in parallel in the airstream, and are heated electrically to 428°F (220°C) above incoming air temperature. The third is used to measure air temperature. When airflow increases, heating element requires higher voltage to maintain temperature. The voltage required is converted into ground pulses, which increase in frequency as air flow increases. ECM uses ground pulse frequency to calculate mass air flow. MAF sensor signals are a measurement of engine load. If a fault is detected in the MAF sensor circuit, substitute values will be used for intake pressure and intake air temperature.