TEST 1: Checking For A Dirty (Contaminated) MAF Sensor
The very first thing to do is to remove the mass airflow sensor (MAF) sensor from its housing and eyeball the two 'hot-wires' in the MAF sensor.
The two hot-wires are normally an off-white to a light gray color, so if they're dirty (contaminated) they will be covered in what appears to be a black fuzz.
We can't just use any type of solvent to clean the MAF sensor with. Here are a couple of very important guidelines on what to use:
- An electronics spray cleaner can be used.
- You can buy it at your local autoparts store (AutoZone, Pepboys, O'Reilly Auto Parts, etc).
- You can buy it at your local electronics store (Radio Shack, Fry's, etc).
- Or you can buy a MAF sensor cleaning spray. Yes, there is one designed just for cleaning MAF sensors.
- This cleaner is made by CRC Industries and its part number is: 05110.
- You can buy it at your local autoparts store (AutoZone, Pepboys, O'Reilly Auto Parts, etc).
- Don't use carburetor or brake clean spray or gasoline.
- These solvents will leave a residue on the wires that will attract dust/dirt and you're back to square one in a few weeks or months.
- Not to mention the harsh solvent can damage the MAF sensor's electronics.
- Also, don't attempt to physically clean the sensor with anything (like a cotton swab) or you may break the wires.
If the MAF sensor hot-wires were not dirty (contaminated), then re-install the MAF sensor back onto its housing and go to TEST 2.
If the MAF sensor hot-wires were dirty (contaminated), clean per the suggestion given above. Then re-install the MAF sensor back onto its housing and road test your Nissan to see if the issue has been solved. If the issue was not solved, then further testing is required, go to TEST 2.
TEST 2: Testing The Power Circuit
The very first thing that we'll do is check that the MAF sensor is receiving 12 Volts.
The wire that feeds this power to the MAF sensor is the wire identified with the letter B in the photo above.
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 for all of your tests. To see an example of a wire piercing probe, check out this link: Wire Piercing Probe. DO NOT insert anything into the female terminal of the connector.
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, these are the test steps:
- Put the multimeter in VOLTS DC mode.
- Do not disconnect MAF sensor connector from the MAF sensor.
- With the red multimeter test lead and an appropriate tool, probe the MAF sensor connector's B circuit as shown in the photo.
- With the black multimeter test lead probe the battery negative (-) terminal.
- Turn key ON with the engine Off.
You should see 12 Volts on the multimeter. Do you have 12 Volts?
CASE 1: The multimeter registered 12 Volts -All is good in the neighborhood. The next step is to make sure that the MAF sensor is getting Ground. Go to: TEST 3.
CASE 2: The multimeter DID NOT register 12 Volts -The MAF sensor is not the problem. Without this voltage the MAF sensor will not work.
The next step is to find out why this power is missing and restore it.
TEST 3: Testing The Ground Circuit
In the previous test we checked that the sensor was receiving 12 Volts. Now we'll check that the MAF sensor is getting a good Ground. This Ground is provided by the ECM internally.
Be careful and take extreme care not to short-circuit this wire to Ground or power as you're probing it.
You can test this circuit with the connector connected to MAF sensor or not.
- Turn key to the OFF position.
- Put the multimeter in VOLTS DC mode.
- With the black multimeter test lead and a wire-piercing-probe, probe the MAF sensor connector's C circuit as shown in the photo.
- Connect the red multimeter test lead to the battery positive (+) terminal.
- Turn the ignition switch to the RUN position.
You should see a voltage of 12 Volts. Do you have that?
CASE 1: The multimeter registered 12 Volts -All is still good in the neighborhood. The next step is to make sure that the MAF sensor is producing a signal. For this test go to: Test 4: Testing The MAF Signal.
CASE 2: The multimeter DID NOT register 12 Volts -The MAF sensor is not the problem. Without a Ground in this circuit, the MAF sensor will not work.
Although it's beyond the scope of this tutorial, your next step is to find out why this Ground is missing and restore it. This will get the MAF sensor back to work.
