Which sensor measures the mass of air entering the engine?

Which sensor measures the mass of air entering the engine?

• A. TPS
• B. MAP
• C. MAF
• D. O2

Answer: (C)

Measuring the actual amount of air entering the engine is done by the MAF sensor. It sits in the intake air stream and directly gauges how much air is flowing into the engine, typically using a heated element whose temperature is kept constant. The engine control unit adjusts fuel delivery based on this measured air mass to maintain the desired fuel–air ratio. The hotter, denser, or faster the incoming air, the more cooling the element experiences, and the sensor reports a higher mass airflow. In contrast, other sensors have different roles: the throttle position sensor tracks how open the throttle is, affecting how much air can enter; the manifold absolute pressure sensor measures pressure inside the intake manifold and can be used to estimate air density, which helps with calculations in certain control strategies but doesn’t directly measure mass flow; and the oxygen sensor monitors exhaust composition to fine‑tune the fuel mix. Since the question asks for the sensor that measures the mass of air entering the engine, the MAF sensor is the direct, best answer.

Measuring the actual amount of air entering the engine is done by the MAF sensor. It sits in the intake air stream and directly gauges how much air is flowing into the engine, typically using a heated element whose temperature is kept constant. The engine control unit adjusts fuel delivery based on this measured air mass to maintain the desired fuel–air ratio. The hotter, denser, or faster the incoming air, the more cooling the element experiences, and the sensor reports a higher mass airflow.

In contrast, other sensors have different roles: the throttle position sensor tracks how open the throttle is, affecting how much air can enter; the manifold absolute pressure sensor measures pressure inside the intake manifold and can be used to estimate air density, which helps with calculations in certain control strategies but doesn’t directly measure mass flow; and the oxygen sensor monitors exhaust composition to fine‑tune the fuel mix. Since the question asks for the sensor that measures the mass of air entering the engine, the MAF sensor is the direct, best answer.