Hello,
I Have a strange screeching noise coming and going in my XC60 D3 2.4D from 2012 when I drive.
It does not go up or down with the rpm of the engine but goes up and down with the speed of the shaft or wheels I assume.
There is no system when it comes and goes regardless of cold/warm engine or outside climate.
It's only while driving and like I thin high rev humming, it can go away for months and suddenly be there again.
Even while driving a steady speed / rpm the high sound can vary up or down. Nearly like a air valve , vacuum squeak.
Has any got any idea of what this thing might be please ?
Kind regards

 

Since the noise happens randomly, I’d suggest checking the driveshaft, wheel bearings, or differential. Problems with these parts can cause on-and-off noises.