Chronic problem with the BMW. I have a code reader and the check engine light occasionally comes on due to the same small leak problem. If you go to MITCHELL ON DEMAND, you will see that this has been an ongoing problem. I too replaced the gas cap, and the light stayed out for months. Now, I dab a wad of petroleum jelly on the gas cap seal. So whatever pressure is leaking out of the spring in the gas cap most likely will not get past the petroleum jelly on the seal. The jelly should be re-added from time to time.
It fixes the problem for 2 months or so, which in my case is about 8 -10 fill ups.Like i said, I did look into the problem and it is a common problem with the BMW. A small leak detected is usually the gas cap, most of the time. Not to say there is no other problem.
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