The PTC Nipple is mounted in the cold air intake pipe that runs from the air filter box to the turbo. It is in the elbow of the pipe, nearest the turbo. It has two vacumm hoses connected that run back to the oil trap. There is also an electrical connector. It looks like your typical piece of electical mumbo jumbo stuff. It is not very large, about the size of a spark plug.

I am not sure what its' actual function is, but it passes the crank case gases back into the engine to be burned. I have been told that it may be a device to heat the gases when the engine is cold. Regardless, mine was blocked and I had way too much pressure in the crank case, causing oil to blow from the filler cap.

When I get the new intake pipe and put it back together, I will let you know.
I can also forward a picture of it if you would like.
Send an email to me: rafuse_d@hotmail.com