How To Test The MAF Sensor (GM 3.8L V6 1996-2005)

TEST 2: Testing The Power (12 Volts) Circuit

If you've reached this point, you've confirmed the MAF sensor is not creating a signal that increases/decreases as you accelerate/decelerate the engine.

There's a good chance that the MAF sensor isn't able to produce a correct signal because it's not getting power. In this test section, we'll check that the MAF sensor is receiving 10 to 12 Volts.

The wire that feeds the MAF sensor with power is the wire labeled with the letter C in the photo above.

NOTE: DO not insert anything into the female terminal of the connector or you run the risk of damaging it. Whatever method you use, the key here is not to damage the female terminal or the wire.

These are the test steps:

1. 1

   Place your multimeter in Volts DC mode.

2. 2

   Disconnect the MAF sensor connector from the MAF sensor.

3. 3

   With the red multimeter test lead and an appropriate tool, probe the MAF sensor connector's C circuit as shown in the photo.

4. 4

   With the black lead of the multimeter probe the battery negative (-) terminal.

5. 5

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

6. 6

   You should see a voltage of 10 to 12 Volts DC.

You should see 12 Volts on the multimeter. Do you have 12 Volts?

CASE 1: Your multimeter registered 10 to 12 Volts. This is the correct and expected result.

The next and last test is to make sure the MAF sensor is getting Ground. Go to TEST 3: Testing The Ground Circuit.

CASE 2: Your multimeter DID NOT register 10 to 12 Volts. Recheck all of your connections and repeat the test. If still no 10-12 Volts registered, then the MAF sensor is not bad. Without power, the MAF sensor will not work. Resolving this lack of power will get the MAF back to work.

TEST 3: Testing The Ground Circuit

In the previous test we checked that the sensor was receiving 10-12 Volts. Now we'll check that the MAF sensor is getting a good Ground.

We're gonna' test the middle wire of the MAF sensor's connector with a simple multimeter voltage test.

These are the test steps:

1. 1

   Place your multimeter in Volts DC mode.

2. 2

   Disconnect the MAF sensor connector from the MAF sensor.

3. 3

   With the black multimeter test lead and an appropriate tool, probe the MAF sensor connector's B circuit (see photo above).

4. 4

   With the red lead of the multimeter probe the battery positive (+) terminal.

5. 5

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

6. 6

   You should see a voltage of 10 to 12 Volts DC.

Let's analyze your multimeter voltage test result:

CASE 1: Your multimeter registered 10 to 12 Volts. This is the correct and expected result and it confirms the MAF sensor is getting Ground.

You can conclude the MAF sensor is bad and needs to be replaced if you have:

• Confirmed that the MAF signal does not increase/decrease as you accelerate/decelerate the engine (TEST 1).
• Confirmed that the MAF sensor is getting 10 to 12 Volts (TEST 2).
• Confirmed that the MAF sensor is getting Ground (this test section).

CASE 2: Your multimeter DID NOT register 10 to 12 Volts. Recheck all of your connections and repeat the test.

If still no 12 Volts registered, then the MAF sensor is not bad. Without Ground, the MAF sensor will not work. Resolving this lack of Ground will get the MAF back to work.