Mass Airflow Sensor

WARNING: This page does not describe the selected car, but rather 31 other vehicles, including the 2003 Mercury Sable, 2003 Mercury Mountaineer, 2003 Mercury Marauder, 2003 Mercury Grand Marquis, and 2003 Lincoln Town Car. However, it is still accessible from the selected car via links, so may be relevant.

Mass Airflow (MAF) sensor is located between air cleaner and throttle body, or inside air cleaner assembly. MAF sensors use a hot wire sensing element to measure amount of air entering the engine. Air passing over the hot wire causes it to cool. The hot wire is maintained at 392°F (200°C) greater than ambient temperature, as measured by a constant cold wire. See Fig 1.

The current required to maintain hot wire operating temperature is proportional to the intake air mass flow. MAF sensor outputs an analog voltage signal to PCM proportional to intake air mass. PCM uses this signal to calculate fuel injector pulse width in order to provide the desired air/fuel ratio. On some applications, MAF sensor input is used in determining transmission Electronic Pressure Control (EPC), shift and Torque Converter Clutch (TCC) scheduling.

Most MAF sensors have Integrated By-Pass Technology (IBT) with an integrated Intake Air Temperature (IAT) sensor.

Fig 1: Cross-Sectional View Of Mass Airflow Sensor (With IBT)

Courtesy of FORD MOTOR CO.