Mass Air Flow (MAF) Sensor Test 3.5L Nissan Pathfinder (2001-2003)

The MAF (mass air flow) sensor on your 3.5L Nissan Pathfinder (2001-2003) can be easily tested with a multimeter. No scan tool is required.

This section includes info that'll make the MAF test on your Pathfinder a breeze and some basic working theory, that I recommend you take a look at before jumping into the tests.

You can find this tutorial in Spanish here: Prueba: Sensor de Flujo de Aire (MAF) 3.5L Nissan Pathfinder (2001-2003) (at: autotecnico-online.com).

APPLIES TO: This tutorial applies to the following vehicles:

• Nissan Pathfinder 3.5L: 2001, 2002, 2003

NOTE: There are 4 other Nissan MAF sensor test articles:

• How To Test The Nissan MAF Sensor Frontier, Quest, Pathfinder, and Xterra 3.3L V6 (1999-2004).
• How To Test The Nissan MAF Sensor: Maxima 3.0L V6 (1995-1999).
• How To Test The Nissan MAF Sensor: Sentra 1.6L 4 cyl. (1995-1999).
• How To Test The Nissan MAF Sensor: Sentra 1.8L 4 cyl. (2000-2002).

Common Symptoms Of A Bad Nissan MAF Sensor

Here's a basic list of symptoms that your Pathfinder will experience when the mass air flow sensor goes bad:

1. MAF Codes that light up the check engine light (CEL) on your instrument cluster.
   • P0100,
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 to follow the test instruction in this tutorial.

I would also recommend using a wire-piercing probe to to test the MAF signal wire. You can see what this tool looks like here: Wire-Piercing Probe.

Circuit Descriptions Of The Nissan MAF Sensor Connector

The mass air flow sensor's connector, on your Nissan Pathfinder, has slots for 5 wires but only has 4 wires attached to it (with one slot being empty). I've labeled the wires with the numbers 1 thru' 4 to help you identify them and to describe what each one does:

• Number 1:
  • Battery Power (12 Volts).
• Number 2:
  • Ground. Provided internally by ECM.
• Number 3:
  • 5V Reference.
• Number 4:
  • MAF Signal.

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 Pathfinder's MAF Sensor Work?

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

This means that since when the Pathfinder's 6 cylinder engine is revved up to, let's say about 2,500 RPMs, the MAF sensor will output a higher MAF signal than when it's just idling at of 900 RPMs. It's as simple as that!

When testing this DC voltage MAF signal with your multimeter, the important thing to know is not an actual Volts DC value at a specific RPM, but to confirm that the MAF voltage signal increases/decreases as engine RPM increases/decreases.

If the MAF sensor has failed, you'll see that its voltage signal output will stay stuck in one value regardless of engine RPM.

In the TEST 4 section of this tutorial, I'll show how you just how to test this so that you can confirm that your Nissan Pathfinder's MAF sensor is bad or not.

TEST 1: Making Sure The MAF Sensor Is Getting Power

The starting point, of your Nissan Pathfinder's diagnostic, is checking that it is receiving 10 to 12 Volts with the key on.

NOTE: Be careful when probing the front of the female terminal (of the connector). The multimeter test lead could damage the female terminal.

OK, let's get this show on the road:

1. 1

   Put the multimeter in Volts DC mode.

2. 2

   Disconnect the MAF sensor from its connector.

3. 3

   Gently probe the female terminal of the connector that connects to the wire labeled with the number 1 with the red multimeter test lead.

4. 4

   Connect the black multimeter test lead to the battery negative (-) terminal.

5. 5

   Turn key ON with the engine OFF.

6. 6

   Your multimeter should register 10 to 12 Volts DC.

Let's take a look at what your test results mean:

CASE 1: Your multimeter registered 10 to 12 Volts. This result indicates that the Pathfinder's MAF sensor is getting juice (power). The next step is to test the Ground circuit, go to: TEST 2: Making Sure The MAF Sensor Is Getting Ground.

CASE 2: Your multimeter DID NOT register 10 to 12 Volts. Recheck all of your multimeter connections and retest. If still no voltage, then this result exonerates the Pathfinder's MAF sensor as the cause of the MAF code or MAF issue, since without this voltage, the MAF sensor will not produce a signal to the computer.

Finding and repairing the source of this missing voltage will resolve the MAF sensor issue with your Nissan Pathfinder.