Frontier, XTerra MAF Sensor Test P0100: Mass Air Flow (MAF) Circuit Malfunction

TEST 2: Making Sure The MAF Sensor Is Getting Ground

So far, you've verified that the MAF sensor on your Nissan Frontier (or Nissan Xterra) is getting juice (10 to 12 Volts DC).

Now you need to verify that it also has a good path to Ground. The circuit that provides this path to Ground is the wire labeled with the letter B.

IMPORTANT: Be careful when testing this wire (circuit), since this wire ends up connecting directly to the fuel injection computer. If you accidentally short it to battery power (12 Volts), you will fry the fuel injection computer.

OK, this is what you need do to:

1. 1

   Place your multimeter in Volts DC mode and disconnect the MAF sensor from its connector.

2. 2

   With the red multimeter test lead and an appropriate tool, probe the MAF sensor wire that is identified with the letter B in the photo.
   
   This will be the green wire of the MAF sensor connector.

3. 3

   Connect red multimeter test lead to the battery positive (+) terminal.

4. 4

   Turn the key to the ON position but don't crank or start the engine.

5. 5

   Your multimeter should register 10 to 12 Volts if Ground is present in the wire.

Let's analyze your test result:

CASE 1: Your multimeter registered 10 to 12 Volts. This result indicates that your Nissan Frontier's (Nissan Xterra's) MAF sensor has a good Ground circuit. The next step is to test the MAF signal, go to: TEST 3: Testing The MAF Signal.

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 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 2.4L Frontier Pickup (or Nissan 2.4L Xterra).

TEST 3: Testing The MAF Signal

Now for the test you signed up for! You're now gonna' see if the MAF sensor is actually measuring the incoming airflow (with your multimeter of course).

Start the engine and let it reach it's normal operating temperature, since it's important to perform this test with a warm engine. You'll be using the DC voltage reading you'll obtain at idle as a base value to diagnose the MAF sensor.

The MAF sensor must be connected to its connector to perform this test.

1. 1

   Probe the MAF sensor wire that is identified with the letter C with the red multimeter test lead. This will be the red wire in the photo above.

2. 2

   Place the multimeter in Volts DC mode.

3. 3

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

4. 4

   Start the already warmed up engine.
   
   Note the Volts DC reading on your multimeter as the engine idles. This reading may be stable (with only small fluctuations) or unstable with very extreme fluctuations. No matter what the instability in the reading, this will be your base voltage reading.

5. 5

   Manually accelerate the engine. The multimeter's voltage value should increase.
   
   The higher you accelerate the engine, the higher the voltage reading on your multimeter.

6. 6

   Let the engine return 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.

7. 7

   The voltage should increase and decrease as you accelerate and decelerate the engine.
   
   If the MAF sensor is defective, the MAF voltage signal will stay fixed in one single value no matter how much you accelerate the engine.

Let's interpret your MAF signal test result:

CASE 1: The voltage reading increased/decreased as you revved up/down the engine. This test result tells you the MAF sensor is working correctly.

CASE 2: The voltage reading DID NOT increase/decrease as you revved up/down the engine. This test result indicates the mass air flow sensor on your Nissan 2.4L Frontier (2.4L Xterra) is bad. Replace the MAF sensor.