Booster check valve question

[tractoman]

I will soon have my kids car home for it’s summer maintenance while he is on summer break. Among other things, I am replacing the check valve and hose to vacuum pump. What is the small vacuum nipple for? I don’t remember his car having a vacuum hose there?
It’s an ‘08 A4 Quattro 2.0 FSI.

[Theiceman]

we went through this a while ago , i think we established it goes to a charcoal canister vale or something. under the fender. only some cars have it.

[tractoman]

Thanks. His car does have a vacuum line there. All is well and check valve replacement was uneventful.