If its a turbo,most likley it is the engine breather hose. The part that it attaches is called the oil trap.there is also a small vaccum hose that attaches to it and goes to the intake manifold.All of this tees into a small y shaped plastic fitting.The fitting will break when you try to remove it so go buy a new hose,tee,small vaccum line and replace it all.Be sure that the vaccum supply nipple on the intake manifold is open so that the engine breathes correctly.