Attached part link has no matching listing to A6 c6.
As first response suggest, check the last service. If fluids/filters are up to date, get your car scanned with vcds.
Has this happened before? If not, do you remember doing anything to/with the car that could've cause any damage?
Any wear would've been impossible to detect but also check for any tear or splits in all piping. could be something simple like slipped breathing hose.