I keep getting the 'Service Engine Soon' light on the dash of my new 135i. Four times now, once a week since I've owned it to be exact. BMW service keeps telling me there is some kind of a minor pressure leak in the fuel tank, and they suspect the gas cap is not on properly since diagnostic tests show no specific problems. Note: I own another BMW (2007 X3) and have never had a problem with my gas cap replacement skills. They simply run the test on the 135i and turn the light off after all tests pass.
I should mention the first time it happened it was before I ever filled up the car, at about 100 miles. The last time I brought it in, I even demonstrated how to replace the gas cap to my SA--and he confirmed I know what I'm doing. He just gave me a new gas cap; we determined (after 3 service visits!) the old one felt loose (turned to the left too easily). The new one still feels a bit loose but tighter than the first one. BUT...after a couple hundred miles it happened again today! FOUR times for the same problem in the first 1100 miles is ridiculous.
Can anybody help? I'm at the end of my rope. This is my wife's car...she's furious with me. Should I invoke the lemon law? The car is fine otherwise (save a minor intermittent oddity with the nav/entertainment buttons losing memory function). There is no engine performance issue...