The mass airflow (MAF) sensor in your BMW can last a long time provided you keep up with your vehicle maintenance. This sensor is responsible for tracking the air that flows into the engine. It sends the air levels to the engine control module so it can make adjustments in the combustion chamber if necessary. Star Motors European lists the signs that your mass airflow sensor is failing below.
You know how your BMW or other European vehicle responds when you press down on the accelerator. If this response is sluggish, it’s possible that the mass airflow sensor has reported incorrect data to the engine control module and you have too much air in the combustion chamber.
If the incorrect data causes the engine control module to increase the amount of fuel in the combustion chamber in error, you may end up with black exhaust smoke pouring out of your BMW’s tailpipes.
Check Engine Light
Usually, when the mass airflow sensor malfunctions, it will send an error code to the engine control module and you will end up with a check engine light warning on your dashboard.
Engine Performance Trouble
If the engine has too much air in it because of the incorrect data relayed by the mass airflow sensor, your engine will stutter and sputter as it tries to perform under fuel-starved conditions. If the engine has too much fuel in it, it will surge forward in spurts even though you have not increased your foot pressure on the accelerator. Both of these engine performance problems can be caused by a failing mass airflow sensor.
Another sign that your engine has too much air and not enough fuel in it is idling roughly. If you’ve noticed that your engine is stuttering while you are idling, it could be that the MAF has convinced the engine control module that the engine has too little air. To compensate for this, the engine control module will increase the air and your engine will stutter.
Poor Fuel Economy
Finally, whether you have too much fuel or too much air in your combustion chamber, you will notice a significant reduction in your BMW’s fuel economy. This is because the engine will burn away any excess fuel that is in the chamber and it will work harder if it is fuel-starved.