I have a 2009 A4 2.0 TFSI with a CDNC engine code and I had the unfortunate pleasure of having to put new pistons in it due to high oil consumption. I am a qualified mechanic and I have taken the engine apart and it is nearly back together again apart from I have a small plastic part which to all intents and purposes it looks something to do with oil but i have no recollection of removing it or where it should go. I found it in a box where I have kept and labelled a lot of the nuts and bolts and the odd part. I attach photos of the part.

Any help greatly appreciated. 

Hi Andreas,. Good to see you're doing your own repairs for your 2009 A4 2.0TFSI. It's a real pain, when you can't find where something should have gone. We all do it, even "Down Under" in Australia, where I live 

Is there a Part # on it at all?

(I thought Audi covered most of the rebuild costs for high oil consumption)

Perhaps it's #12  06H 103 156 This site below has always been helpful to me. I'm not a mechanic, but enjoy doing most of my own repairs.

https://audi.7zap.com/en/rdw/audi+a4+s4+avant+quattro/a4q/2009-636/1/103-103002/#12