How To Test The GM MAF Sensor (3.1L, 3.4L, 4.3L, 5.0L and 5.7L)

This is one of the easiest mass air flow sensors to Test. The following Test is an On Car Test that checks the performance of the MAF sensor with the engine running. You'll test this GM MAF sensor with a multimeter that can read Hertz (Hz) Frequency. No scan tool is required or any other expensive testing equipment.

In the box titled Applies To: (in the column on the right), you'll find a complete list of GM makes and models (and Isuzu) that use this type of MAF sensor. Now, in case this is not the article you're looking for, there are also 3 other GM MAF sensor test articles:

  1. How To Test The GM Mass Air Flow Sensor: GMC Savana Van and Chevy Express Van 4.3L, 5.3L, 6.0L Engines (2003-2008)
  2. How To Test The GM Mass Air Flow (MAF) Sensor: 4.8L, 5.3L, 6.0L, and 8.1L V8 Engines (1999-2010)
  3. How To Test The MAF Sensor on 3.1L, 3.3L, and 3.8L Buick, Oldsmobile, Pontiac (1988-1996)
  4. How To Test The GM MAF Sensor: Buick, Chevy, Olds, Pontiac 3.8L V6 Engines (1996-2005)

You can find this tutorial in Spanish here: Cómo Probar el Sensor MAF GM 3.1L, 3.4L, 4.3L, 5.0L, y 5.7L (at:

Is The MAF Sensor Just Dirty (Contaminated)?

The most important thing to do before starting with the mass air flow sensor test, is to make sure your MAF sensor's wires aren't contaminated with dirt (since the tests in this article assume the MAF sensor isn't contaminated).

Why? Because this MAF sensor is a hot wire sensor type that easily becomes contaminated with dirt and stuff if the air filter isn't performing its job.

This contamination will appear as a type of ‘fuzz’ on the two wires of the sensor. You can see an example of a dirty MAF sensor here: Dirty MAF Sensor Example (Fly Stuck in MAF Sensor).

This contamination will cause the sensor to produce a lower reading to the ECM (Engine Control Module = Fuel Injection Computer).

The most common symptom of this contamination is a hesitation or a time-lag in engine response that is felt after the accelerator pedal is depressed. Other symptoms may include but are not limited to: higher tailpipe emissions and diagnostic codes that may illuminate the "Check Engine" light.

If the sensor wires are dirty, use an electronics spray cleaner to clean them with. This in itself may solve your problem. I don't recommend using carb or brake clean spray. These solvents can damage the sensor.

Also, don't attempt to physically clean the sensor with anything. You'll find all autopart stores sell the correct cleaning spray. If you'd like to see the MAF sensor cleaning process explained step by step click here: How To Clean The Mass Air Flow Sensor.

Common Symptoms Of A BAD MAF Sensor

This list is not all inclusive but it does contain the most common symptoms of a BAD MAF sensor are:

  1. The CHECK ENGINE LIGHT (CEL) on your instrument cluster is lit nice and bright with one of the following codes:
    1. P0101   Mass Air Flow System Performance.
    2. P0102   Mass Air Flow Low Frequency.
    3. P0103   Mass Air Flow High Frequency.
  2. Lean and/or Rich code(s).
  3. Fuel Trim code(s).
  4. A tremendous lack of power upon acceleration.
  5. Black smoke coming from the tail-pipe.
  6. Vehicle may idle rough and stall.