Originally Posted by BrianNC81

The Problem: BMW has announced that certain emissions components on 2009-2011 3 Series, X5, and X6 diesel models including the SCR catalyst, DEF mixer, and the EGR valve may overstate vehicle mileage. This may cause emissions standards to be exceeded and illuminate the check engine light. This in turn could cause affected models to fail U.S. emissions tests.

I wonder if this is also causing the gunk build up in the EGR/Cylinder head.