TEST 1: Testing The MAF's Power (12 V) Circuit

Making Sure The MAF Sensor Is Getting Power. Mass Air Flow (MAF) Sensor Test 3.5L Nissan Pathfinder (2001-2003)

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

Just a reminder, do not test for this voltage by probing the front of the MAF sensor's connector. The procedure I recommend for you to use (to accomplish all of the tests below) is to use a back probe or a wire piercing probe. You can see an example of this tool here: Wire Piercing Probe.

Whatever method you use, the key here is not to damage the female terminal or the wire. Again, be careful. Use common sense and take all necessary safety precautions.

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

  1. With your multimeter in VOLTS DC mode.
  2. Probe the MAF sensor wire, that's identified with the number 1 in the photo, with the RED test lead.
  3. Connect the black multimeter test lead to the battery (-) negative terminal.
  4. Turn Key On with the engine Off.
  5. If all is good, then your multimeter should display 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.

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.

TEST 2: Testing The MAF's Ground Circuit

Making Sure The MAF Sensor Is Getting Ground. Mass Air Flow (MAF) Sensor Test 3.5L Nissan Pathfinder (2001-2003)

Since the MAF is getting power, the next step is to verify that it has a good path to Ground.

The circuit that provides this path to Ground is the wire labeled with the number 2 and is provided internally by the fuel injection computer. Do not use a test light for this test.

Alright, let's get started:

  1. Turn key to the OFF Position.
  2. Multimeter in VOLTS DC mode.
  3. With the black multimeter test lead and an appropriate tool, probe the MAF sensor wire that is identified with the number 2 in the photo.
  4. Connect the red multimeter test lead to the battery positive (+) terminal.
  5. Your multimeter should register 10 to 12 Volts.

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 has a good Ground circuit. The next step is to test the MAF signal, go to TEST 3.

CASE 2: Your multimeter DID NOT register 10 to 12 Volts. Recheck all of your multimeter connections and try the test again. If still no voltage, then this result exonerates the Pathfinder's MAF sensor as the cause of the MAF code lighting up your check engine light (CEL) or MAF issue, since without this Ground, the MAF sensor will not produce a signal to the computer.

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

TEST 3: Testing The 5 V Reference Signal

Making Sure The MAF Sensor Is Getting The 5 Volt Reference Signal. Mass Air Flow (MAF) Sensor Test 3.5L Nissan Pathfinder (2001-2003)

Now, you need to verify that the fuel injection computer is sending the MAF sensor 5 Volts on the circuit labeled with the number 3 in the photo.

These are the test steps:

  1. With the key in the OFF position.
  2. Probe the MAF sensor wire that is identified with the number 3 in the photo with the red multimeter test lead.
  3. With the multimeter still in Volts DC mode.
  4. Connect the BLACK lead to the battery (-) negative terminal.
  5. Turn the key on and notice the Voltage on your multimeter.
  6. The multimeter should display 5 Volts.

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

CASE 1: The multimeter registered 5 Volts. This test result tells you the circuit is OK and the computer is doing its job. The next step is to verify that the Pathfinder's mass air flow sensor is creating a MAF signal the computer can use. For this test go to: TEST 4: Testing The MAF Signal.

CASE 2: The multimeter DID NOT register 5 Volts. This test result means you must find the cause of these missing 5 Volts. Without this voltage the MAF sensor will not function.

Nissan Vehicles:

  • Pathfinder 3.5L
    • 2001
      2002
      2003