How To Test The GM MAF Sensor Express and Savana Van (2003-2008)

The mass air flow sensor on your 2003-2008 GMC Savana van or Chevy Express van can be easily tested in three steps and without a scan tool. All you need is a digital multimeter that can read Hertz frequency.

At the bottom of this page you'll find all of the years of the Savana and Express vans this article applies to. 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 (Early Type): Buick, Chevy, Olds, Pontiac 3.1L, 3.4L, 4.3L, 5.0L, 5.7L V6 Engines (1996-2005)
  2. How To Test The GM MAF Sensor: Buick, Chevy, Olds, Pontiac 3.8L V6 Engines (1996-2005)
  3. How To Test The GM Mass Air Flow (MAF) Sensor: 4.8L, 5.3L, 6.0L, and 8.1L V8 Engines (1999-2010)
  4. How To Test The MAF Sensor on 3.1L, 3.3L, and 3.8L Buick, Oldsmobile, Pontiac (1988-1996)

En Español Puedes encontrar este tutorial en Español aquí: Cómo Probar el Sensor MAF de Express y Savana Van (2003-2008) (en: autotecnico-online.com).

Symptoms Of A BAD GM MAF Sensor

The most obvious one is that the CHECK ENGINE light (CEL) will be on on your instrument cluster and driving you nuts. Here are a couple of others:

  1. A MAF sensor diagnostic trouble code (DTC) stored in your vehicle computer's memory.
    1. P0101, P0102
  2. Lean and/or Rich diagnostic trouble code(s).
    1. P0171, P0174
  3. Fuel Trim diagnostic trouble code(s).
  4. No power when you accelerate the car or truck.
  5. Black smoke coming from the tail-pipe.
  6. Your car or truck or SUV may idle rough and stall.

What Tools Do I Need?

You'll need a digital multimeter that can read Hertz (Hz) frequency (don't have a digital multimeter that can read Hertz frequency? Click here to see my recommendations: Buying A Digital Multimeter For Automotive Diagnostic Testing). As mentioned earlier, you don't need an automotive scan tool to test the MAF sensor. Having said that... a scan tool is one of those MUST have tools to be able check and diagnose today's modern cars and trucks, but for the tests in this article you don't need one.

Circuit Descriptions Of The MAF Sensor Connector

Circuit Descriptions Of The MAF Sensor Connector. How To Test The GM MAF Sensor Express and Savana Van (2003-2008)

The MAF sensor on your Express van (or Savana van) has 5 wires coming out of the connector. Each wire (circuit) has a specific job to do and below you'll find the description. Each of the 3 Tests, that make up this article, will use these circuit descriptions:

  1. Circuit labeled 1:
    1. Air Temperature Sensor Circuit
  2. Circuit labeled 2:
    1. Air Temperature Sensor Circuit
  3. Circuit labeled 3:
    1. Ground Circuit.
  4. Circuit labeled 4:
    1. Power (12 Volts) Circuit.
  5. Circuit labeled 5:
    1. MAF Signal Circuit.

I did not include the color of the wires because as long as you're able to identify them by the number in the photo, you'll be OK. Also, the color of the wires in the photos may not be the color of the wires of the MAF on your specific vehicle.... and again this is no cause for concern.

Basic Working Theory of the GM MAF Sensor

The Fuel Injection Computer needs to know the amount of air the engine is breathing to inject the correct amount of fuel (among several things) and keep your GM van idling or running smooth. For this, the PCM relies on the mass air flow sensor.

The MAF sensor's job is to measure the amount of air the engine is breathing at any given RPM. It then converts this measurement into a Hertz frequency reading (as measured by a digital multimeter that can read Hz frequency) and shoots it to the PCM. Here's what it looks like on a digital multimeter:

  1. At an idle of about 680 RPM's, the MAF sensor outputs about 3.2 K Hertz.
  2. At about at 1500 RPM;s the MAF signal output is about 4.2 K Hz.
  3. At 2500 RPM's it hovers around 5.2 K Hz.

As you can see, the more air the engine breathes (or the higher the RPM's) the higher the MAF output signal becomes, and of course the less air the engine breathes, the lower the reading on your digital multimeter. Now, in testing the MAF sensor, you won't be looking for a specific Hertz (Hz) number at a specific RPM... but for crazy fluctuations in the signal that don't correspond to the amount of air entering the engine or NO SIGNAL AT ALL. OK, crash course is over, let's start testing.

GM Vehicles That Use This MAF Sensor

  1. Chevrolet
    1. Express Van (1500, 2500, 3500) 4.8L, 5.3L, 6.0L
      1. 2003, 2004, 2005, 2006, 2007, 2008
  2. GMC
    1. Savana Van (1500, 2500, 3500) 4.8L, 5.3L, 6.0L
      1. 2003, 2004, 2005, 2006, 2007, 2008