I have heard of this before.
Earlier I had a E46 330d where the turbo was worn out and needed to be replaced.
At that incident I saw the inside of the intake manifold. It was all black and filled with some black residue from the EGR inlet. At that point the car had done +300.000km
I had it until 542.000km and had no problems with that myself though.
And yes, it is possible to blind the EGR and code it. I have seen this on other coding fora.
'06 E91 330dA Sparkling Graphite
|19" VMR703 Black Matte