What goes on this nipple

[Skunkworks76]

So as I was addressing some issues with my S5 I found what appears to be a vacuum nipple near my throttle body. Although I don't feel any vacuum when I put my finger on it. Anyone know if something should be there and if so what. It is a 2009 S5.

[hahnmgh63]

I don't have an older 4.2 S5 so I can't say for sure but that may be for the heated intake/throttle body circuit. Someone probably disconnected it, common. There was probably a coolant hose connected to this and has been plugged somewhere. Unless you live in an area with sub-zero temperatures it's fine. a common performance mod on 4.2's that have it. Might rob a BHP or two when the engine/coolant is hot when it's working. RS5 has a similar system for it's two throttle bodies, I've removed them on my RS5.