Mass Air Flow Sensor

The Mass Air Flow Sensor is responsible for measuring how much air enters the engine and communicates it to the central computer, thus balancing the air/fuel mixture and ensuring proper engine operation.

What is the MAF Sensor?

The MAF sensor is the component that feeds the mass combination between fuel and air that must enter the engine for its ignition and correct operation. All fuel injection engines have this sensor. The function of the MAF sensor is to send signals to balance the mixture and achieve engine efficiency.

It is the Mass Air Flow sensor that has a hot wire or platinum wire inside.  This must be kept at about 200 degrees temperature in order to process the signal and send it to the engine control unit.

What is the MAF sensor used for?

sensor maf

The main function of the MAF sensor is to measure, employing a resistance wire, the amount of air that passes into each cylinder of the engine. With the information sent by the MAF, the computer can know the temperature at which the platinum wire is. In this way, it can regulate how much oxygen the engine needs to run without overheating.

How does the Mass Air Flow Sensor work?

The MAF sensor is equipped with a flow meter that monitors the displacement of air volume into the engine's intake system. Simply put, the flowmeter consists of a wire that emits high temperatures. However, the air passing through the wire emits an electrical signal to dissipate the heat.

It must be said that the wire is very sensitive to the air that reaches it, so the temperature of the motor depends on how hot or cold the flowmeter is. That is to say, the voltage value that emits the wire is nothing more than a signal of permission of admission of air to the engine of the vehicle. The computer then cools the air in the engine.

Types of MAF Sensor

There are three types of MAF sensors, the vane or VAF, and the so-called Karman Vortez. However, these models are old and the most commonly used in modern vehicles is the MAF sensor.

Common MAF sensor faults

Accumulated dust and dirt can cause the Mass Air Flow to malfunction. Therefore, you should take care that the air filter is changed regularly, this ensures that clean air enters the sensor. Although you will not be left with an accident because of this, you will have performance problems with the engine, such as:

  • Black smoke in the exhaust indicates too little air and too much gasoline.
  • Difficulty in maintaining the vehicle's idle speed.
  • Possible explosions during start-up.

How to test if the MAF sensor is working?

If you suspect that the MAF sensor is defective, you can do some electrical testing using a multimeter. You should have the connector plugged in and check the wires one by one, following the steps below:

Tap the multimeter to the B power terminal to check that the sensor is receiving current.

Check that the voltage is 5 but never below or above this value.

Now, place the multimeter in the continuity position. With the tips touch the metal parts. A beep indicates that the ground is correct.

Finally, the signal is measured with the vehicle running. Place the multimeter in voltage position. With one tip you touch the ground and with the other, you prick the terminal. With someone's help, ask them to accelerate the engine a little and verify that the signal increases.

When malfunctions occur with the mass air flow sensor the automotive scanner throws fault codes. Here is the meaning of the most common ones related to the MAF:

  • P0100: This error states problems with the sensor circuit. The frequency is not in the expected range. That is, the airflow sent is insufficient for the engine.
  • P0102: It also indicates an air frequency below what is required, which means that the sensor signal is wrong.
  • P0103: Indicates a higher than expected voltage output.
  • P0104: This code is an unstable signal sent by the MAF Sensor to the computer mainframe.

How to clean the Mass Air Flow Sensor?

Visually check the Mass Air Flow to see the general condition of the wires and if there is dirt adhered. Also, check that its connector is not loose. During road trips, the hot wire can accumulate dust, bugs, and even small oil particles. The result will be a vehicle with less power.

To clean it, remove the air filter cover and disconnect the terminal where the MAF sensor is incorporated. Gently grasp the sensor and avoid contact with the thin wire. Its fragility is such that any contact can damage it, which means replacing the component.

Once you have the sensor in your hands, see if the wire is in good condition or broken. If the latter is the case, there is nothing to do as you must replace it. On the other hand, to clean it you need an anti-sulfate spray that makes the electrical contacts as good as new. When it is clean, the wire should have a grayish color. Now, you can put everything back together and clean the area where the air filter goes with a soft cloth.

Mass Air Flow Sensor Location

This small air mass flow sensor you can locate near the air filter and throttle body of the vehicle. From there, it can measure the airflow entering the engine. You can find out the exact location of the MAF sensor by acquiring the car's electrical diagrams.


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