Mass Air Flow Sensor

Frequently Asked Questions

Completely known as the mass air flow meter, it's more commonly referred to as an MAF meter, air meter, or sometimes just MAF. The Mass Air Flow (MAF) sensor is a key component of a vehicle's electronic injection system. It is located between the air filter and the engine intake manifold. It’s responsible for measuring the amount of air entering the engine. The ECU or PCM then calculate the correct amount of fuel needed for an optimal air-fuel ratio by this information. A car’s air-fuel ratio needs to be optimal to ensure uninterrupted combustion and enhanced engine performance. The ideal AFR is 14.7:1 (14.7 lb. of air to 1.0 lb. of gasoline). This is important in calculating the amount of fuel to add to achieve the proper air-fuel ratio (AFR). But the air-fuel ratio can vary under different circumstances.. Acceleration requires AFR of up to 12:1, while cruising requires levels as low as 22:1. If the MAF sensor fails, the ECMs may not be able to properly calculate fuel injection. This will cause all sorts of problems with your car.

Step1: Park the vehicle and allow the engine to cool for 10 minutes.

Step2: Put on gloves and safety glasses.

Step3: Open the hood of your vehicle and look toward the air box and throttle body, between these parts is the MAF sensor.

Step4: To remove the MAF sensor

Step5: Use a screwdriver to unscrew the MAF sensor from your vehicle. 10-15 blows around the inside of the sensor are sufficient.

Step6: Allow the MAF sensor to dry for 1 hour.

Step7: Screw the MAF sensor back into place and plug in the connector.

1. Find your MAF sensor and its connector. Most of the time, your MAF sensor is located somewhere between your air filter box and your throttle body.

2. Find its connector and wires, there are a ground wire and a signal wire, which is the wire that sends the voltage from your MAF sensor back to the ECU.

3. Turn our key to the "on" position without turning the engine on

4. Get our multimeter, turn it on, and put our settings on 20 DC volts.

5. Grab our black test lead and connect it to the battery ground. Make sure you get a good connection, use clamps if you have to.

6. Get our test lead and start testing these pins on the harness side, the harness side being the side that's not coming from your MAF sensor and is coming from your ECU. 7. Touching these pins, and the one that gives us any voltage, either 5 or 12 volts, we're going to know that's our voltage supply wire or our constant.

8. Look at the back of the connector and write down which wire is your constant wire.

9. Find our ground wires. This harness again has two ground wires. One is going to be your constant ground, and the other one's going to be your sensor ground.

10. Turn the multimeter to Ohm settings

11. Turn off the car and remove the key.

12. Test the other pins for resistance to ground.

13. Replug key. Back probe the two remaining wires and measure our voltage reading from our MAF sensor during engine operation.

14. Turn on the engine.

15. Attach my test leads to these two paper clips.

16. Measure our voltage. The signal wire should be 0.60-0.80 volts idle. If you get battery voltage, you are probing the power lead. Increase the engine speed between 2,500 and 3,500 rpm. The voltage should increase to approximately 1.5 to 3.0 volts. Keep in mind that as the engine speed increases, the air flow increases.

1. Dark exhaust smoke
2. Check engine light comes on
3. Difficulty starting your car
4. Engine stalls after shortly starting or when idling
5. Worse fuel efficiency than usual
6. Hesitation and jerking during acceleration
7. The engine hiccups
8. Rough Idle
9. Engine hesitation, dragging or surging

Step1: Disconnect the vehicle's negative battery terminal.

Stpe2: Locate the MAF sensor.

Stpe3: Disconnect the MAF sensor electrical connector. Detach the wire harness from the MAF sensor.

Step4: Remove the sensor.

Step5: Push the MAF sensor out of its housing.

Step6: Connect the new sensor. Position the new MAF sensor.

Step7: Reconnect the electrical connector.

Step8: Reconnect the negative battery post.

Step9: Test and calibrate. Start the engine and watch for check engine light or other indication of sensor problems.

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