This happens only once in a while, but sometimes when I arrive at home, after parking in my garage, switching the car off, closing the garage, and exiting the car, I hear what sounds like some type of large fan operating. I then discover tha the sound comes from the engine area, and when I put my hand behind the exhaust, I can feel warm gas still exiting. I don't think that my engine is completely on though, because of the way it sounds, but there's still gas coming out of the tailpipe. I don't hear the characteristic clatter of the engine's metal parts... just hear what sounds like a fan. Whenever this happens, I turn the car back on, then off. Then it stops.

I don't have comfort access. Does anybody know what could be happening? Thanks... I hope this isn't a repost. I tried doing a search but couldn't find a match to this issue.