How To Test The MAF Sensor (1.6L Mazda Protegé)

TEST 1: Checking The MAF Sensor Power Circuit

To get our MAF sensor diagnostic on its way, we'll make sure that it's getting power.

This power comes in the form of 12 Volts and is provided with the Key On Engine Off (KOEO) and Key On Engine Running (KOER).

The wire that's responsible for feeding this voltage to your Mazda's MAF sensor is the wire labeled with the number 1 in the photo above.

OK, this what you'll need to do:

1. 1

   Place the multimeter in Volts DC mode.

2. 2

   Connect the red multimeter test lead to the wire identified with the number 1 in the image above.
   
   This is the white with red stripe (WHT/RED) wire of the MAF sensor connector.

3. 3

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

4. 4

   Turn the key to the ON position (RUN position).

5. 5

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

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

CASE 1: The multimeter recorded 10 to 12 Volts DC- So far so good, since this test result tells you that your Mazda's mass air flow (MAF) sensor is getting power.

The next step is to make sure that the MAF sensor has a good Ground in the wire labeled with the number 2. For this test, go to: TEST 2: Checking The MAF Sensor Ground Circuit.

CASE 2: The multimeter DID NOT record 10 to 12 Volts DC. Make sure that you're testing the correct wire, that your connections are OK, and repeat the test.

If your multimeter still doesn't register between 10 to 12 Volts, then you've found a problem that needs to be corrected. Without these 10 to 12 Volts, your Mazda's MAF sensor won't work.

TEST 2: Checking The MAF Sensor Ground Circuit

In TEST 1, you confirmed that your Mazda's MAF sensor is getting power. Now you need to make sure that it's also getting Ground.

This Ground is provided by the wire labeled with the number 2 in the photo above.

You can check this Ground with a 12 Volt automotive test light or a multimeter. The test instructions below assume that you'll be using a multimeter.

NOTE: This Ground is provided directly by the PCM, so be careful and don't short this wire to battery 12 Volts or you'll fry your Mazda's PCM.

OK, this is what you need to do:

1. 1

   Place the multimeter in Volts DC mode. We're gonna' test the presence of Ground by doing a simple multimeter voltage test.

2. 2

   Connect the black multimeter test lead to the wire identified with the number 2 in the photo above.
   
   This is the black (BLK) wire of the MAF sensor connector.

3. 3

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

4. 4

   Your multimeter should immediately register 10 to 12 Volts DC.

Let's interpret your test results:

CASE 1: The multimeter recorded 10 to 12 Volts DC. This multimeter test result tells you that the MAF sensor on your Mazda is getting a good Ground.

The next step is to make sure that the MAF sensor is working and outputting a MAF signal on the wire labeled with the number 3. For this test, go to: TEST 3: Checking The MAF Sensor Signal.

CASE 2: The multimeter DID NOT record 10 to 12 Volts DC. Make sure that you're testing the correct wire, that your connections are OK, and repeat the test.

If your multimeter still doesn't register voltage, then you've found a problem that needs to be corrected. Without this Ground, your Mazda's MAF sensor won't function.

Repairing this Ground issue will get the MAF sensor back on its feet.