Mass Air Flow (MAF) Sensor Test 2.4L Nissan D21 Hard Body (1990-1995)

Testing your Nissan D21 pickup's MAF sensor, to see if it's bad or not, can be done in three easy and simple tests. They're all done with a multimeter, since you don't need an automotive scan tool to do it and this article will show you how.

This part of this test article includes some handy information that you'll need to make testing the MAF on your D21 as easy and as pain free as possible. This MAF test article covers the Nissan D21 Hard Body pickup (with a 2.4L 4 Cylinder) for the years: 1990, 1991, 1992, 1993, 1994, and 1995. There are 4 other Nissan MAF sensor test articles:

In Spanish You can find this tutorial in Spanish here: Prueba: Sensor de Flujo de Aire (MAF) 2.4L Nissan D21 Hard Body (1990-1995) (at:

Common Symptoms Of A Bad Nissan MAF Sensor

This list covers the majority of symptoms I've seen with this type of Nissan mass air flow sensor:

  1. MAF codes that light up the check engine light (CEL) on your instrument cluster.
  2. MAF sensor malfunction that DOES NOT light up the check engine light (CEL).
  3. Lean and/or Rich code(s).
  4. Fuel Trim code(s).
  5. A tremendous lack of power upon acceleration.
  6. Black smoke coming from the tail-pipe.
  7. Bad gas mileage.
  8. Vehicle may idle rough and stall.

What Tools Do I Need?

The most important tool that you're gonna' need is a digital multimeter (or an analog multimeter), this bad boy doesn't have to be an expensive one. A scan tool (automotive diagnostic scanner) is not needed. I would also recommend using a wire-piercing probe to to test the signal of each wire (to see what this tool looks like, click here: Wire-Piercing Probe.

Circuit Descriptions Of The Nissan MAF Sensor Connector

Mass Air Flow (MAF) Sensor Test 2.4L Nissan D21 Hard Body (1990-1995)

The mass air flow sensor on your Nissan D21 pickup has three wires attached to it. You'll notice that the photos (in the image viewer) have the MAF connectors lettered A thru' C (if you look closely at the MAF sensor itself on your D21 pickup, you'll see these letters on it too). I'll be using these letters for the circuit descriptions. Here's the description of each circuit below:

  • Letter A:
    • Power (12 Volts).
  • Letter B:
    • MAF Signal.
  • Letter C:
    • Ground.

I recommend using a wire-piercing probe to test the signals in the wires, since this method will be the most effective and easiest way of getting to the signal. If you need to see what this tool looks like, click here: Wire-Piercing Probe. Independent of the method you use, be careful not to damage the wire(s). Take all safety precautions.

How Does The D21 MAF Sensor Work?

The mass air flow (MAF) sensor's job is to measure the amount of air that the engine is breathing. And this measurement of the air flow is sent to the D21's fuel injection computer as an analog DC voltage signal.

To be a little more specific since D21's four cylinder engine will breathe in more air at, let's say, 2,500 RPMs than when it's sitting at an idle of 900 RPMs this will cause the MAF sensor to send a higher DC voltage signal to the computer than at idle. It's as simple as that!

When testing this DC voltage MAF signal, the important thing to know is not an actual Volts DC number at a specific RPM, but to look for crazy and extreme fluctuations in the MAF voltage signal that don't correspond to the actual air intake (RPMs) of the engine or NO SIGNAL AT ALL. In the TEST 3 section of this article, I'll show how you just how to test this so that you can confirm that your Nissan pickup's MAF sensor is bad or not.

Years Of The Nissan D21 Pickup This Article Applies To

  • Nissan
    • D21 pickup 2.4L
      1. 90, 91, 92, 93, 94, 95

Nissan Vehicles:

  • D21 Pick Up 2.4L
    • 1990