The Symptoms of a Bad Mass Airflow MAF Sensor
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The MAF or mass airflow sensor is an essential part of a fuel-injected engine. It measures the amount and the density of the air that is entering the intake manifold at any given moment. The information is then relayed to the engine CPU, so the computer can adjust the amount of fuel entering the combustion chanmber, hence producing the ideal air/fuel ratio. This enhances engine performance and fuel economy.
The function of the MAF sensor sounds simple enough, doesn’t it? But did you know that it is often one of the most neglected parts inside the engine bay? And did you also know that the mass airflow sensor is one of the most common problems that can illuminate the check engine light in your console?
Where can I Find the MAF Sensor in my Vehicle?
Park the car in a safe and level area. Make sure the engine is cool enough before you proceed. Pop open the hood and check the area between the airbox or the air filter and the intake manifold of the vehicle. Do you see a plastic hose that connects the airbox to the manifold? Good. The MAF sensor is usually located between or directly after the air filter and the throttle body manifold.
It is a small electronic device that measures the amount of air flow inside the intake system. You will notice that the MAF sensor is placed between the air filter and the throttle body, which means that a dirty or clogged air filter will significantly affect the performance of the mass airflow sensor.
What will a bad MAF do?
These are the symptoms of a bad MAF sensor:
- Engine stalling, almost immediately after starting the car. Since the engine CPU can’t measure the amount of airflow, the engine will stall immediately after starting the car.
- Lack of power and poor acceleration. If the engine CPU is unable to correctly measure the air flow, it will assume the engine needs more fuel and will will switch to a rich air/fuel ratio. This will not only result in poor MPG, but your car will feel lethargic and slow.
- Unstable idling, especially when the A/C is on. There are a lot of causes of unstable idling, but a bad MAF sensor is one of them. If you turn on the A/C, the engine will need to adjust the idling speed of the engine. If the MAF sensor is not working properly, the engine will have a hard time to maintain a stable idling speed.
- Engine hiccup. This condition is usually caused by dirty or fouled spark plugs and a dirty throttle body, but this is also a symptom of a bad MAF sensor.
- Unable to start the car, even after turning the engine for a couple of times. This is usually indicated by a check engine light on the console.
How Can I Avoid MAF Sensor Problems?
If you drive an older car (or if you bought a used car) then you should replace the MAF sensor after 50,000 to 70,000 miles. Better yet, you should follow the service recommendations of your vehicle. There are times when the mass airflow sensor will fail without notice, even if your has has no symptoms of a bad MAF sensor. So it is a good idea to replace the MAF sensor according to the maintenance guidelines of your car.
Always clean or replace the air filter when you change the engine oil. If the air filter is always dirty, then harmful contaminats like sand and dust will enter the combustion chamber. It will also restrict the air flow inside the engine. If you are using an aftermarket air filter or air box, make sure to clean the filter cone or the filter element whenever you change the engine oil, and replace the filter element whenever necessary.
You can also use commercial spray cleaners to clean the MAF sensor. However, you should be careful in cleaning the MAF sensor. If you break the wire inside the sensor, then you should prepare shelling out at least $100 for a new unit.
If there is a check engine light in your car, you can eliminate the guesswork by getting yourself an OBD2 scanner like the Oxgord CAN OBD II Scanner Tool or the OBDII Scan Tool Foseal Scanner Adapter. This will save you a lot of time and money when your are diagnosing the trouble code of your vehicle.
The MAF sensor is a durable kit, but failure will result due to poor vehicle maintenance. Always clean or replace the air filter so you can extend the life of your mass airflow sensor.
Vince G here with ScannerAnswers. Mike and Matt made me fill out this bio… I write on this site once-in-a-while when I’m not fishing or biking. I love fast cars and on weekends I sometimes work on them. I help with this site because I believe everyone should own and be able to use a wireless bluetooth OBD2 scan tool.