RickNY

We have a 2015 Impala, and while it is parked in our garage, it emits a high pitch noise every few seconds that lasts 3-4 seconds and repeats.. The car doesn't get used that often in the winter, so it will often go a couple of weeks in between getting started.. The noise occurs while it is just sitting there and hasn't been run recently, so it does not appear to be related to something remaining after the engine has been run.

We also have a 2013 Malibu parked in the same garage that gets used daily -- and that will make various electric noises as well at random times hours after its been turned off.. Its very quiet in the garage, and we go out there to smoke, so we often get the opportunity to hear these things..

I will add that in both vehicles -- the fob for the Impala is left in the car while its parked in the garage, and the Malibu is left with the key in the ignition, but off.. Not sure if that has a bearing on it.

Any ideas what this might be? Is it possible its some sort of Onstar related thing performing diagnostics or something?