Help: What does this do ?

[Hellas]

So your E90 still had the wrong type. Where is this situated in the engine. I would like to check mine.

Nope, he still has the E46.

Here is the E90 though; Same posistion on the cylinder head:

http://realoem.com/bmw/showparts.do?model=VC32&mospid=48480&btnr=11_3668&hg=11&fg=15