Mass Airflow Sensor Image

Mass Airflow Sensor

The mass airflow sensor (MAF) provides feedback to the powertrain control module (PCM or engine computer) proportionate to engine load. The more load that is put on an engine, the greater the volume of air that is entering the engine at any one moment in time, but accurate airflow is only one part of the measurement. The computer must also correct for barometric pressure, humidity and other dynamics of the intake air. Therefore, the MAF measures the actual weight of the air entering the engine as opposed to simply the volume.

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How Does it Work?

  • Intake air passes through the venture of the MAF and is sampled by an element heated wire, grid or film
  • The PCM uses this load measurement as a major corrective factor for fuel delivery, ignition timing and other outputs

How Is It Made?

  • Generally, the MAF consists of a cast aluminum or glass-filled nylon body with protective screens on either end
  • The measurement element is either positioned directly in the airflow or off to the side and fed by a sampling side channel

Why Does It Fail?

  • Heat cycling
  • Vibration in the engine compartment
  • Failure of the electronics
  • Problems with the element

What are Symptoms of Failure?

  • Malfunction indicator lamp (MIL) or check engine light will come on
  • Hesitation and stalling

What Are the Consequences of Failure?

  • Engine may have reduced power, also known as limp home mode