Originally Posted by k4u2luz2
I have the exact same problem in my 2006 and it is killing me. I have checked all the things you have all mentioned and still can't diagnose. The only thing I can think of is, it must be the bearing on the impeller shaft of the turbo. Anyone...open for more ideas.
My case turned out to be an exhaust leak (of all things!). The corrugated hard pipe on the EGR was cracked. When the pipe finally split the squeal became a more recognizable sound and I was able to locate it. Even if it seems intact, pull it off and check it. Bet it comes out in more than one piece!
Hope that helps!