How does a mass air flow (MAF) sensor function?

A mass air flow (MAF) sensor plays a crucial role in an engine's operation by measuring the amount of air entering the engine. This function is essential for optimizing the air-fuel mixture, which is a critical factor for efficient combustion. The MAF sensor provides the engine control unit (ECU) with real-time information about the air mass being drawn into the engine.

By knowing how much air is entering, the ECU can adjust the fuel injection accordingly, ensuring that the correct ratio of air to fuel is maintained for efficient combustion. This optimization leads to better engine performance, improved fuel efficiency, reduced emissions, and overall system stability.

The other options reflect different aspects of engine management but do not pertain to the primary function of the MAF sensor. For instance, measuring engine temperature is typically the job of a temperature sensor, while detecting exhaust emissions is handled by O2 sensors or similar devices. Though the ECU does optimize fuel injection, it's not the MAF sensor that directly controls the injection rate; rather, it supplies the necessary data for the ECU to make those adjustments.