I've had a check engine light coming on and then going off for about three weeks on my 2007 S hatchback (R56) with about 90k miles. The code is P115c. I thought it might be a faulty gas cap so I replaced. Looked promising for a few days but the light came on again this morning. There is a small difference in power when the CEL comes on. When I clear the code, power returns until the light comes on again. There is a stutter on start up every now and then and there have been a few stutters while driving. I have listened closely to the engine and I don't hear any hissing while running or after shutdown so I don't think it is a leaking valve cover or something similar. I don't see any obvious areas where oil is leaking either. My question is this, is this the mass air flow sensor? Any thoughts about diagnosing further given the unhelpful manufacturer's code. If it is the MAF, can it be cleaned or does it have to be replaced? If it can be cleaned, how? It looks like a tube housing so I don't think I will be able to take anything apart on it (and would prefer not to since I understand that these parts are very sensitive). Any help would be appreciated

 

Worth trying to clean the MAF. I just use generic MAF sensor cleaner from any auto parts store. That's cleared up a lot of issues for me in the past that I was worried were much more severe. It'll only cost you $10-15 and then you'll know whether or not that's the issue.