TEST 4: Testing The MAF Signal

Testing The MAF Signal With A Multimeter. Mass Air Flow (MAF) Sensor Test 3.5L Nissan Pathfinder (2001-2003)

OK, now for the stuff you signed up for, this last test will either condemn the MAF sensor as being bad or exonerate it. Read the following directions carefully before starting the test.

It's important that you warm up the engine to perform this test. So start it up and and let it reach it's normal operating temperature.

IMPORTANT:. The MAF sensor must remain connected to its electrical connector to be able to read it MAF signal. For this reason you need to use a back-probe or a wire piercing probe to read the MAF signal.

OK, let's get this party started:

  1. With the key in the OFF position.
  2. Probe the MAF sensor wire that is identified with the number 4 in the photo with the red multimeter test lead.
  3. Connect the BLACK lead to the battery (-) negative terminal.
  4. Put the multimeter in Volts DC mode.
  5. Crank and start the already warmed up engine.
  6. Note the Volts DC reading on your multimeter as the engine idles. You should see about 1.2 Volts on your multimeter. Now, this reading may be stable (with only small fluctuations) or unstable with very large fluctuations. No matter what the instability in the reading, this will be your base voltage reading.
  7. Manually accelerate the engine as you observe how the multimeter's voltage value increases. As a reference point, at around 2,500 RPM's you should see about 2.5 Volts.
  8. The higher you accelerate the engine, the higher the voltage reading on your multimeter.
  9. When you let go of the accelerator cable linkage on the throttle body and the engine returns to idle, the voltage value on the multimeter should return to the base voltage value you recorded in step 5. This voltage reading may not be the exact same but should be very close.
  10. Repeat this as often as you need to verify that the Volt numbers on the multimeter rise and decrease smoothly every single time.
  11. If the MAF sensor is good, these readings will not spike up and down crazily but will correspond to the amount of air the engine is breathing at the different RPMs you're accelerating the engine to.

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

CASE 1: If the voltage reading increased and decreased smoothly according to the amount of acceleration you caused, then the Pathfinder's MAF sensor is working correctly.

Here's why: If the MAF sensor were faulty, your multimeter's reading would have stayed stuck at one value no matter how much you revved up the engine. Since the value went up as you revved up the engine, then you can consider the MAF sensor working correctly.

CASE 2: If the voltage reading DID NOT increase and decrease smoothly according to the amount you accelerated or decelerated the engine, then the mass air flow sensor on your Nissan Pathfinder is bad. Replace the MAF sensor.

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Nissan Vehicles:

  • Pathfinder 3.5L
    • 2001