Mass Air Flow Sensor

Mass Airflow Sensor and Intake Air Temperature Sensor
The MAF sensor is a combined MAF sensor and IAT sensor.

Mass Airflow Sensor Description
Airflow is determined by the cooling effect of the intake air passing over a "hot film" element contained within the device. The higher the air flow the greater the cooling effect and the lower the electrical resistance of the "hot film" element. The signal from the device is then used by the ECM to calculate the MAF into the engine.

The measured airflow is used in determining the fuel quantity to be injected in order to maintain the stoichiometric air fuel ratio required for correct operation of the engine and exhaust catalysts. Should the device fail there is a software backup strategy that will be evoked once a fault has been diagnosed. A fault is detected if the MAF signal exceeds the maximum or minimum threshold for a given speed range or the difference between the calculated load and the actual MAF signal is too great.