A mass air flow sensor is used to find out the mass of air entering a fuel-injected engine. The air mass information is necessary for the engine control unit (ECU) to balance and deliver the correct fuel mass to the engine. Air changes its density as it expands and contracts with temperature and pressure. In automotive applications, air density varies with the ambient temperature and altitude, and this is an ideal application for a mass sensor.
Intake Air Temperature sensor (IAT)
The intake air temperature sensor is mounted to the air duct housing. The sensor detects intake air temperature and transmits a signal to the ECM. The temperature-sensing unit uses a thermistor that is sensitive to the change in temperature. Electrical resistance of the thermistor decreases in response to the temperature rise.