I bought this car about a month ago and no nothing about volvos. As I was replacing the cam sensor I barely touched this unknown piece. Its round and has a black hose going into it. Have looked everywhere online and can't seem to find it anywhere

 

Can you post a pic? Check out a few useful web sites: Volvotips as a shop manual and Shop OEM Volvo parts & accessories ? Volvo Parts Warehouse for OEM part numbers and picture diagrams.

 

Cant help you unless you post a picture.