I just had the Cylinder Head Expansion hose fail on me on the highway last night on the way to see a friend. That was a PITA to remove on my F30 B46. You have to remove the ECU harness and holder to access the hose under the intake manifold. The part has had 3 revisions. In the F31 and F30 made in 2017, the part has long since been discontinued, and after looking at the part itself, I can see why.
I found the latest revision: 17125A05950 on ebay since all the major part sellers had it listed as back ordered. 50$ after shipping and tax.