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.
This MAF test article covers the Nissan Pathfinder SUV (with a 3.0L V6) for the years: 2001, 2002, and 2003. 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).
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).
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:
- MAF Codes that light up the check engine light (CEL) on your instrument cluster.
- MAF sensor malfunction that DOES NOT light up the check engine light (CEL).
- Lean and/or Rich code(s).
- Fuel Trim code(s).
- A tremendous lack of power upon acceleration.
- Black smoke coming from the tail-pipe.
- Bad gas mileage.
- 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. And this measurement of the air flow is sent to the 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 on your Pathfinder with your multimeter, 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 Pathfinder's MAF sensor is bad or not.
Pathfinder Application Chart
- Pathfinder 3.5L
- 01, 02, 03
- Pathfinder 3.5L