This piece replaces OEM part: 1J0122109AQ. Sitting next to the timing belt area under the coolant expansion ball, it connects three parts of the coolant system together on the transverse 20v 1.8T engine.
The original plastic pipe tends to fail via a hairline crack at the seam where the Y splits off. At the most inopportune time, hot pressurized coolant will spew all over the top of the engine and pressure will drop. The low coolant light will eventually pop up in the dash cluster as engine temperature creeps towards the red zone. In most cases, this story ends with a tow truck, ruined plans, and wasted money at the local repair shop.