I have a high pitched whine under the hood with engine off. Seems localized near fuse box area. Never heard before on 2008 Panel. Need forum help. Thanks

 

Need a little more info is the noise there with the key off and the engine off? is it there just after the engine is shut down and gos away after few sec.

 

Engine off, key off. Whine still going when I retired last night, and gone this morning. Car started fine, so apparently no battery drain. Stumped.

 

Could have been your cooling fan being on if the engine was hot?

I know with my SS, I hear a few noises after I shut her down, usually ends with the throttle blade closing

 

My sons old cavalier z-24 did same thing. Research found out when 1 of the 3 diodes goes in the alternator it will whine even with engine off. Disconnected battery and changed alternator. Problem solved. He had around 130k miles on it. Hope this helps.

 

Well it's not easy to say. I do know that the car performs test when the car is at rest like testing the o2 sensor heaters and what not. But the tests don't take all that long and don't usually make a lot of noise.

 

Possibly a relay in the fuse box (remove the cover and check)? Maybe the ABS which is near there?

You may need to do a little further "digging" under the hood, for some valid answers.