Now the vacuum leak is a common problem found in all models of BMW between the engine and the mass airflow sensor. Due to the vacuum leaks, unmetered air is entering into the system and the actual airflow seems to be higher than the mass airflow sensor measures. Generally, the effect of the vacuum leak is more noticeable ate idle conditions when the airflow is lower down. Go through the slide to know about the causes behind vacuum leaks in BMW X3.