How does a MAF sensor work in air intake measurement?

• A. It measures the mass or flow of air entering the engine, providing data to the engine computer to adjust fuel delivery.
• B. It monitors exhaust gas temperature.
• C. It detects misfires in cylinders.
• D. It regulates fuel vapor purge.

Answer: (A)

Measuring how much air actually enters the engine is crucial for dialing in the right amount of fuel. A MAF sensor does exactly that by sensing the mass of air flowing into the intake and sending a signal to the engine computer so fuel delivery can be adjusted accordingly.

Most modern MAF sensors use a hot-wire or hot-film element placed in the air stream. The element is heated, and as air flows past it, it cools the element. The control electronics keep the element at a constant temperature by varying the electrical current needed to resist cooling. The amount of current (or the resulting signal) changes with the air mass flowing past, and that signal is translated by the ECU into how long or how much fuel to inject.

This direct measurement lets the ECU account for different engine loads, speeds, and air conditions, and it works together with other sensors to maintain the correct air-fuel ratio. The other options describe different sensors or purposes (like exhaust temperature, misfire detection, or fuel vapor control), which aren’t what a MAF sensor does.