What does the MAF sensor provide to the engine computer?

• A. The mass or flow of air entering the engine, used to adjust fuel delivery.
• B. Exhaust gas temperature.
• C. Oil pressure.
• D. Crankshaft position.

Answer: (A)

The MAF sensor tells the engine computer how much air is entering the engine, by providing a signal that represents the mass flow rate. This information lets the ECU meter the correct amount of fuel to maintain the proper air–fuel ratio as engine speed and load change. Most MAF sensors use a hot-wire or hot-film element: as air flows past the heated element, it cools it, and the electrical current required to keep the element at a constant temperature changes in proportion to the air mass flowing in. The ECU uses that signal to adjust fuel injector pulse width accordingly.

Other sensors measure different things (exhaust gas temperature, oil pressure, crankshaft position) and aren’t used to determine how much fuel to inject, which is why they’re not the correct source of this information.