How To Test The MAF Sensor (2011-2013 1.6L Ford Fiesta)

TEST 2: Making Sure The MAF Sensor Is Getting Power

The MAF sensor needs power, in the form of 12 Volts, to function and produce a viable MAF signal the fuel injection computer can use.

In this test section, we're gonna check that the wire I've labeled with the number 6 is delivering 10 to 12 Volts to the MAF sensor.

We'll do a simple multimeter voltage test to confirm the presence of this voltage with the key in the RUN position (but with the engine off).

IMPORTANT: Be careful not to damage the front of the connector or female terminal with the multimeter test lead, or you'll need to replace the connector.

These are the test steps:

1. 1

   Disconnect the MAF sensor from its electrical connector.

2. 2

   Place your multimeter in Volts DC mode.

3. 3

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

4. 4

   Gently probe the female terminal that connects to the wire I've labeled with the number 6 with the red multimeter test lead.
   
   This wire should be the green with orange stripe (GRN/ORG) wire of the MAF sensor connector.

5. 5

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

6. 6

   You should see 10 to 12 Volts on the multimeter.

Let's interpret your test result:

CASE 1: The multimeter registered 10 to 12 Volts. This is the correct result.

The next step is to make sure the MAF sensor has Ground, for this, go to: TEST 3: Making Sure The MAF Sensor Is Getting Ground.

CASE 2: The multimeter DID NOT register 10 to 12 Volts. Double check all your multimeter connections and test again.

If you still don't see 10 to 12 Volts, you can conclude that the MAF sensor itself is not at fault as it will not function without 12 Volts.

TEST 3: Making Sure The MAF Sensor Is Getting Ground

OK, so far you have:

• Confirmed that the MAF sensor's voltage output is stuck in one value regardless of engine speed (TEST 1).
• Confirmed that the MAF sensor is getting 10 to 12 Volts (TEST 2).

In this last test section, we're now gonna make sure that it's getting Ground from the fuel injection computer.

The wire that delivers this Ground to the MAF sensor is the one I've labeled with the number 4 (see photo above).

Let's get going:

IMPORTANT: Be careful not to damage the front of the connector or female terminal with the multimeter test lead, or you'll need to replace the connector.

IMPORTANT: This Ground is provided by the fuel injection computer internally. Be careful not to connect this wire to battery 12 Volts, or you'll fry the computer. The multimeter voltage test I'm suggesting in the instructions below is a safe way to check for the presence of Ground in this circuit.

These are the test steps:

1. 1

   Disconnect the MAF sensor from its electrical connector.

2. 2

   Place your multimeter in Volts DC mode.

3. 3

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

4. 4

   Gently probe the female terminal that connects to the wire I've labeled with the number 4 with the black multimeter test lead.
   
   This wire should be the white with brown stripe (WHT/BRN) wire of the MAF sensor connector.

5. 5

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

6. 6

   You should see 10 to 12 Volts on the multimeter.

Let's see what your test results mean:

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

You can conclude that the mass air flow (MAF) sensor is faulty if you have:

• Confirmed the MAF sensor's signal is stuck in value regardless of engine speed (TEST 1).
• Confirmed the MAF sensor is receiving 10 to 12 Volts (TEST 2).
• Confirmed the MAF sensor is receiving Ground from the PCM (this test section).

CASE 2: Your multimeter DID NOT register 10 to 12 Volts. This test result indicates the MAF sensor is not receiving Ground.

Recheck all your multimeter connections and test again. If your multimeter still doesn't read 10 to 12 Volts, you can conclude that the MAF sensor itself isn't faulty as it won't work without Ground from the fuel injection computer.

Your next step is to figure out why this Ground is missing and restore it.