Mass Air Flow Sensor

Definition

The Mass Air Flow (MAF) Sensor is an intake system component that measures the volume and density of air entering the engine's intake manifold. The engine computer requires this precise mass reading to calculate the correct amount of fuel needed to achieve complete combustion.

The MAF sensor typically operates using a heated wire element suspended in the intake stream. The sensor measures the current required to keep the hot wire at a constant temperature as passing air cools it. A higher mass of entering air results in more cooling, prompting the sensor to output a higher voltage signal. If dirt, debris, or oil coats the wire, it reports inaccurate measurements, leading to fuel delivery imbalances, rough idling, or stalling.

Failure of the MAF sensor or its wiring triggers diagnostic trouble codes such as P0100, P0101, P0102, and P0103. A dirty or vacuum-leaked MAF sensor can also cause lean system codes like P0171 or P0174 due to unmetered air leaking into the intake manifold behind the sensor.