How to Check the BMW 330i Air Mass Meter for Problems
The air mass meter, also known as the mass airflow meter, is an integral component of the computer-controlled engine found in most modern cars like the BMW 330i. It measures the volume and density of air entering the engine then sends the information to the engine computer. This computer then uses the measurement to adjust spark timing, fuel delivery, and spark advance. When the air mass meter is faulty, you may experience a rough idle, poor gas mileage, and even stalling. In order to keep this from happening, you have to know how to identify problems with this component.
Activated "Check Engine" light (CEL) on the dashboard
When the CEL is on, it could be due to numerous problems with your engine including the air mass meter--you will have to read the codes from an engine code scanner to learn what the problem is. It's considered safe to drive around even when the light is on. However, once it flashes you must get it checked out immediately. Do remember, though, that when you drive around with the CEL on, your car's engine will not be working at its peak. Because of this, you may experience a loss in power and a decrease in gas mileage. It is therefore recommended that you take care of the problem as soon as you can.
Using the engine code scanner
Spotting problems using the scanner is easy, because it already has pre-programmed problem codes that it can identify. The engine code scanner works by comparing the values output by the air mass meter to the expected values that it should be getting. This simple check-up helps diagnose problems with pretty much every component in the engine.
To examine any possible problems, plug the device into a jack found in or near the driver's side fuse box. It will then automatically scan the entire engine and give out codes. In order to know what these codes mean, refer to the engine code scanner or the car owner's manual. The usual error codes relating to the air mass meter are P0171, P0172, P0174, and P0175.
Other symptoms and troubleshooting tips
Along with the CEL being lit, other signs that the BMW 330i air mass meter include sudden loss of power, slow increase in acceleration, knocking and pinging sounds in engine, and poor gas mileage. Regardless of whether the CEL is lit up or not, if you notice any of these symptoms, take out the air mass meter to replace it.