How they work

MAF System

The Mass Air Flow Sensor measures the amount of air volume flowing into a car’s engine, and sends the Electronic Control Unit (ECU) a voltage that represents the airflow.

  • Currently the most common MAF sensor is the plug-in hot wire type which is located inside the intake air duct between the air filter and the throttle body. This consists of a heating resistor, intake air temperature measurement resistor (for compensating intake air temperature), intake air  temperature sensor, and control circuit (printed circuit board).
  • A portion of the intake air from the air cleaner is bypassed into the hot-wire measurement area, where the intake airflow volume is measured. The hot-wire type MAF Sensor responds to temperature changes in the heating element. Changes in the resistance value and current of the heating element are converted into proportional voltage in the control circuit, and then sent to the ECU to calculate the amount of engine intake air volume.
  • The intake air temperature sensor also detects the intake air temperature and outputs it to the ECU. Responding to this signal, the ECU judges the air density and corrects the fuel injection quantity.