Mass Air Flow (MAF) Sensor Test 3.0L Nissan Quest (1993, 1994, 1995)

TEST 2: Making Sure The MAF Sensor Has Ground

OK, now know that you have confirmed that your Nissan Quest's MAF is getting power. The next step is to check that it also has a good path to Ground.

Ground is fed to your Quest's MAF sensor by the wire identified with the letter B in the photo above.

To check for the presence of Ground, we're gonna' do a simple multimeter voltage test.

Here's the test:

1. 1

   Turn key to the OFF Position and place your multimeter in Volts DC mode.

2. 2

   Disconnect the MAF sensor from its connector.

3. 3

   Connect the black multimeter test lead to the MAF sensor wire identified with the letter B in the photo.
   
   Use a back probe or a wire piercing probe to check the wire.

4. 4

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

5. 5

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

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 Quest'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. Verify that all of your multimeter connections are connected securely and try the test again. If still no voltage, then this result lets you know that the Quest's MAF sensor is not the cause of the MAF trouble 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 Quest Mini-Van.

TEST 3: Testing The MAF Signal

OK, now for the test you signed up for! Testing the mass air flow sensor's output signal. Read the test steps carefully and familiarize yourself with them, before doing the test.

To perform this test and obtain a correct result, the Quest's engine must be at normal operating temperature. So, you'll need to start up the Mini-Van and let the engine warm up.

A good MAF sensor will produce a MAF voltage signal value that will increase when you accelerate the engine and decrease when you decelerate the engine.

If the MAF sensor is defective, the MAF voltage signal value will stay stuck in one value when you accelerate/decelerate the engine.

IMPORTANT: This test must be done with the MAP sensor connected to its connector. To access the MAF signal in the wire, you'll need to use a back-probe on the connector or a wire piercing probe on the wire. To see an example of this tool and where to buy it, go here: Wire-Piercing Probe.

OK, this is what you'll do:

1. 1

   Place your multimeter in Volts DC mode.

2. 2

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

3. 3

   Ground the black lead at the battery negative (-) terminal.

4. 4

   Crank and start the already warmed up engine.

5. 5

   Note the Volts DC reading on your multimeter as the engine idles. At idle and with a fully warmed up engine, you should see about 1.2 Volts DC on your multimeter.
   
   This reading may fluctuate a bit, but no matter what the instability in the reading, this will be your base voltage reading.

6. 6

   Manually accelerate the engine. The voltage reading on your multimeter should increase.
   
   At around 2500 RPMs you should see about 2.4 Volts DC on the multimeter.

7. 7

   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.

8. 8

   Repeat this as often as you need to verify that the voltage value increases/decreases when you accelerate/decelerate the engine.

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

CASE 1: The voltage reading increased and decreased smoothly and in a linear fashion as you accelerated and then decelerated the engine, then the Quest's MAF sensor is working correctly.

CASE 2: The voltage reading DID NOT increase and decrease smoothly as you accelerated and then decelerated the engine, then the mass air flow sensor on your Nissan Quest is bad. Replace the MAF sensor.