What is the primary function of a "MAF" sensor?

The primary function of a Mass Air Flow (MAF) sensor is to measure the airflow entering the engine. This measurement is critical because the engine control module (ECM) uses the data from the MAF sensor to determine the optimal air-fuel mixture for combustion. By accurately measuring the amount of air entering the intake manifold, the ECM can adjust the fuel injectors accordingly to ensure efficiency and performance. This helps in maintaining emissions standards and maximizes the engine's power output.

The other options refer to different sensors with distinct roles in the vehicle's operation: measuring fuel pressure involves a fuel pressure sensor that monitors fuel delivery, measuring exhaust temperature is the function of an exhaust temperature sensor commonly used for monitoring catalytic converter efficiency, and measuring engine temperature relates to a coolant temperature sensor that ensures the engine runs at the appropriate operating temperature. Thus, the MAF sensor specifically focuses on airflow measurement crucial for engine performance and efficiency.