BMW: service engine soon light, 2003 bmw 330i, bmw 330i

Question
It seems that everytime I put gas in my 330i bmw, the service engine soon light comes on. Do you think I have to replace the gas cap, or what should I do? My car is a 2003 bmw 330i.

Answer
In all the years I have been working on B.M.W. vehicles, I honestly have not put on that many gas caps. The things I have found for the most part are either the strap holding the gas cap to the body of the vehicle gets caught under the lip of the cap, causing a slight leak or the cap gets installed at a slight angle getting a leak. I recommend to people to make sure #1, not to fill their vehicles while it is running. #2 make sure the cap is on straight and click it about 3 times. Another thing that will cause this (you won't find this one in the books) is overfilling the vehicle. Let the nozzle do its job. Fill it until it shuts off then pull the nozzle out. If you do these things and it still has a check engine light on, have the tank venting system checked. The pump that checks the fuel system for leaks may be bad. I have seen more of that than caps bad. And last but not least. With fuel prices on the rise, we have seen people putting aftermarket lock caps on their vehicles and found them to be leaking. Hope this helps you.