I was bringing my dog in tonight and I heard a low hum coming from my garage. There is NOTHING on in my garage, so I decided to investigate. After some walking around in the cold, I realized it was my car (2014 WRX) that is making the noise. The car is off, no key even in it, and the noise sounds like it is coming from the back quarter of the car, around the rear tire on the driver's side. The best way I can describe it is that it sounds like an air pump that you would have on a fish tank. There is literally NOTHING in my car that is on, or that would be making that noise. If you put your ear to the fender, you can really hear it. What am I hearing?
Thanks in advance!