Boost401 is correct, it's the 4-way check valve that connects to the turbo recirculating valve (N249). I broke that very same check valve last week while removing my PCV system. You can order just the check valve if you want, but there is a vac hose that is heat-shrunk (or glued maybe?) to it that you will find difficult to remove from the broken part without cutting and reattaching to the new check valve.
I actually ended up ordering p/n 078-145-733-G, which is both the check valve and the attached vac hose. I got mine from ECS, though when I searched for the above complete part, it said it wasn't a match for my '04 2.7t... but it is. Here's a photo of old vs new:
And a picture of the bag with p/n that it came in from ECS:
You can find photos I took of it in my 2.7t here: