When the ignition is on, the engine is off and I'm outside of the car I can hear a very loud high-pitched whine, like the sound a cathode ray tube makes, or the ringing of light bulbs that shouldn't be on a dimmer switch, but louder.

It sounds like it comes from under the hood, but it's really hard to pinpoint.

You can't hear it inside the car.

I assume this is normal! It should keep the mice out.

 

Could be the fuel pump, which is normal. My Mazda makes this noise too when I'm in the garage.

Be aware, with ignition on, battery drains pretty quickly. I experienced this on a cross country in a 2000 Saab 9-5 couple years back. I was about to turn the engine on, but right before that wife and I was talking about where to go first. In about 10 minutes, the battery died and needed a jump start.

 

Do you have LED headlights? I've noticed the same sound and found it's coming from fans inside the LED headlights. With the bonnet open and using a flashlight you can see the fans through the clear plastic that is on the top back section of the lights.

Just opening the drivers door makes the fans spin up for some reason. If I don't start the car, the fans will stop after about a minute.

 

My wife makes a high pitched whine, when I take the corners fast!

 

No LED headlights, and it doesn't stop.

 

Power steering fan or pump maybe?

 

Here's a video, if you can stand me breathing like an obscene phone caller.

I thought it could help me find the source, it didn't.

When I opened the hood I could hear a slight whirr along with it, you can hear it in the video if you have headphones on, so I guess it could be mechanical.

Strangely, when I was at the engine it sounded like the noise was coming closer to the firewall, and maybe deep in the engine, but on the video it gets louder near the front.

I'm getting winter tires this week or next, I will ask then.