5 Symptoms of a Bad Mass Air Flow Sensor
Has your engine been performing poorly, stalling, or using less gas lately? A faulty mass air flow sensor (MAF) could be to blame. This critical engine control component monitors the air entering your engine to optimize performance.
Let’s take a look at the most common symptoms of a faulty air flow sensor and how much it might cost to replace a MAF sensor.
5 Most Common Symptoms of a Faulty MAF Sensor
The mass air flow sensor acts as the eyes and ears for your engine’s internal computer. But what happens if it starts sending false information?
All hell can break loose inside. The MAF is responsible for telling the Engine Control Module (ECM) exactly how much air is entering the combustion chamber. Without an accurate airflow reading, the ECM gets confused about how much fuel is in it, and the whole delicate balancing act goes awry.
If too much or too little gas is delivered to the cylinders, the engine will run lean or rich. Performance will suffer and you will lose the stable performance you were used to.
The good news is that your car will exhibit certain symptoms when the MAF sensor fails. If you notice two or more at once, it’s a good indication that the MAF sensor is the culprit sending bad data.
1) Rough Idling
If the air mass sensor is defective, the engine control unit will not receive any information from it. As a result, the engine control unit will not know how much fuel it needs to inject into the cylinder. This can cause the engine to idle roughly or rev freely when you park or stop the vehicle. Watch the tachometer on your dashboard to see if the RPMs are fluctuating rapidly when idling. If this is the case, you may have a bad mass airflow sensor.
2) Engine Stalls
You may be able to start the car and everything seems fine. However, shortly after you start driving, the engine may stall out unexpectedly. This will prompt you to restart the engine.
If you continue to experience this engine stalling issue, try taking your car to your nearest auto mechanic before the engine fails to start at all. If the car was already idling rough before this symptom occurs, the stalling is further evidence that the mass airflow sensor is faulty.
3) Hesitation when accelerating
If you press the accelerator to accelerate your car and feel hesitation when trying to go faster, your mass airflow sensor may be faulty. You can definitely confirm this when the hesitation is followed by a jerk. When you try to drive faster, your car starts to shake violently. These are all signs that your engine is not getting the right amount of air and fuel.
4) Engine running too rich or too lean
A rich fuel-air mixture in the combustion chamber means there is more fuel than necessary relative to the amount of air in the cylinder. If the fuel-air mixture is lean, there is not enough fuel relative to the amount of air in the cylinder for optimal combustion. In either case, it can cause issues with your engine’s combustion process by not producing enough power or consuming too much fuel.
The worst part is that if you don’t keep an eye on your fuel economy, you may not even notice this problem. If you notice that you’re using less gas, it’s probably one of two cases:
You can check this with an OBD2 scanner.
5) Poor fuel economy
When a faulty air mass sensor causes the engine to work too hard, you can expect poor fuel economy. The engine control unit doesn’t know how much air mass is there, so it can pump too much fuel into the engine’s cylinders. The more fuel used per combustion, the greater the impact on your wallet at the pump.
This is how a mass air flow sensor works
As air enters your engine from the outside, the mass air flow sensor detects the mass of this air.
From there, the device can tell the injectors exactly how much fuel to inject into the engine cylinders. This balances the air to fuel ratio and promotes combustion. See how all these components work together in this way?