Mass Air Flow Sensor (MAF)

A mass airflow sensor (MAS) determines the mass of air entering a vehicle's fuel injection engine, and passes that data to the Engine Control Unit, or ECU. The air mass information is necessary for the ECU to correctly balance and deliver the correct amount of fuel to the engine. When a vehicle's mass airflow sensor is faulty or defective it can cause a variety of problems, and usually results in very poor performance from your engine.

An airflow sensor

There are several designs of MAF sensors, but the most common by far is the hot wire MAF sensor. The hot wire MAF has two sensing wires. One wire is heated and the other is not. The microprocessor (computer) inside the MAF determines the amount of air entering the engine by how much current is required to keep the hot wire about 200 ℉ hotter than the cold wire. Whenever the temperature difference between the two sensing wires changes, the MAF will either increase or decrease the current to the heated wire. This equates to more air into the engine or less air into the engine. Sounds complex right?

Symptoms of a Faulty Mass Air Flow Sensor

A faulty mass airflow sensor will cause problems similar to low compression or low vacuum, and will also show symptoms similar to when your vehicle has low fuel pressure from a faulty fuel pump. Here are some of the most common symptoms of a faulty mass airflow sensor:

- The engine is very hard to start or turn over

- The engine stalls shortly after starting

- The engine hesitates or drags while under load or idle

- Hesitation and jerking during acceleration

- The engine hiccups

- Excessively rich (excess fuel) or lean(inadequate fuel) idling

If you believe your car has a faulty mass air flow sensor, and brings up a code (the check engine light we Nigerians always ignore), take it to a qualified mechanic so that a complete computer diagnostic can be run. In most cases, a faulty mass flow sensor has a specific code that will generate during computer diagnostics, and is usually easy to determine with computer testing equipment.

The position of an airflow sensor in a Toyota sedan

How to Clean a Dirty Mass Airflow Sensor

Generally, you'll want to clean your mass airflow sensor either every six months, or every time you change your oil. Cleaning it when you change or clean your air filter will be a good way to save both time and money.

i. Locate the Sensor

Locating the sensor

You can't clean what you can't find. It is most times located on the air intake system before the throttle body. If in doubt, please consult your owner's manual. Download one if you can't find yours.

ii. Remove the Sensor

To clean your mass airflow sensor, first, you must take it out. This is done by using a screwdriver to loosen the screws and pluck it out. When removing the sensor, be sure to never touch the wires. A disconnected mass airflow sensor can't electrocute you, but the wires are delicate and small. Breaking one will require a replacement. 

For extra safety, I take out the negative terminal of my battery whenever I do any electrical work on my car. It is safer and will reset the ECU to clear error codes.

iii. Clean the Sensor

Next, you have two choices. The cheapest option would be to take your mass airflow sensor and place it in a plastic bag filled with rubbing alcohol (methylated spirit). Take the bag and move it around, making sure the alcohol washes all of the dirt and grime from the sensor. Another option would be to buy a special mass airflow sensor cleaner, and spray it onto your sensor, but as stated before, this is more expensive.

iii. Dry and Reinstall the Sensor

Please note that the setup in the images may differ from your car. The cleaning product also may differ from what you can get to buy at your local shop. 

After cleaning your mass airflow sensor with either the cleaner, or rubbing alcohol, let it sit in a clean place till it's dry,  generally for 20 minutes or more. The sensor has to be completely dry before it can be reinstalled in your car, otherwise you may damage it. Replace it and that's all. 

Once the service has been completed, reconnect the batter terminals correctly and start the engine and allow the computer to recalculate feedback data and make necessary adjustments. 

Read more on the air intake system here; The Air Intake System

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Email; vverteautosevcs@gmail.com 

Phone; 09137103730 

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