The 2.0T FSI’s pcv system has gone through several revision changes. Earlier valves failed rather easily, causing boost pressure to creep into the crankcase. Checkvalves would leak and pressure diaphragms would rip. Symptoms include oil coming out of the valve cover gaskets or oil cap, reduced gas mileage and power or increased oil consumption. An unsteady idle is another symptom and severe cases will cause a code to be set. This latest one seems to be a bit more robust than previous versions. The check valves are spring loaded now instead of free floating for more positive engagement. If you want to stay stock here are the latest part numbers.
The latest pcv system part numbers are 06F129101P for the front pcv valve and 06F103215B for the rear breather tube with check valve. The 06F129101P part number only works on rear breather tubes that have a built in check valve. Certain VIN’s / model years have breather tubes that do not have rear check valves. The only way to be sure it to pull it off and check for the valve. Here’s some excellent information for replacing the PCV valve and breather tube. The link also shows the Eurojet check valve solution so just ignore it if you are not going that route.