So, for a couple weeks now, I’ve had an odd whining in my car. I can’t really tell where exactly the sound is coming from, but it’s especially noticeable when I start the car.

The whining starts low pitched, and gradually goes higher and higher until you can’t hear it anymore – kinda sounds like some scifi thing charging up.

My check engine light was on, but it was the exhaust A/F sensor that had the grounding strap come off and I’ve since reattached.

Any idea what the whining could be?