Hi everyone! I have a crazy thing happening with my 2007 328i. Every few thousand miles my gas cap indicator lights up, goes off, then the service engine soon light comes on and stays on. I've taken it to the shop and they can't find anything wrong. Having said that, they haver tried changing the gas cap and a few other things. They did a "fuel tank ventilation system & purge air system, minor - not present." This seems to happen after I hit some bumps on the road. Any ideas?