Every once in a great while, we hear a vibration noise coming from our 2014 Subaru Forester. It sort of sounds like a little buzzer, or a small electric motor is whirring. It seems to be coming from the driver's side rear wheel. It is very intermittent. We have only noticed it occurring when the car is off and parked. Sometimes it's right after we've driven it, but other times it may start up hours or even days after we've used the car. It lasts for a few minutes, then stops. Any ideas what's causing the noise?
It's the fuel EVAP system running a self-test. Quoth the manual (page 8):
Noise from under the vehicle
You may hear a noise from under the vehicle approximately 5 to 10 hours after the engine is turned off. However, this does not indicate a malfunction. This noise is caused by the operation of the fuel evaporation leakage checking system and is normal. The noise will stop after approximately 15 minutes.
Not sure, but this seems like it may be the purge for the fuel tank. It would be pushing vapors through the charcoal canister. It is about the only thing I can think of which would be coming from that area of the car and could be making that sort of noise on a completely random/intermittent basis.