It is an engine oil coolant hose. It runs to the oil cooler, which is a dual processing unit. Oil flows through one side, and antifreezeengine coolant flows through the other.. The hose you are talking about carried antifreeze to the cooler, and then to the engine.
My car has a 4" long hose 1/4" ID in that location and it is a drain for coolant leaks in
the heater core [like a tiny radiator].
the firewall is between the passanger compartment, behind the dashboard and the engine compartment.
There are several firewall holes.The firewall is the wall that divides the engine from the passanger compartment.Under the windshield.
The firewall is the part of the car's body that seperates the engine from the passanger compartment.
PASSANGER SIDE OF ENGINE TOWARDS THE BOTTOM OF THE FIREWALL
Between firewall and passanger side engine valve cover
A possible leak somewhere from one of the hoses. Likewise the leak could be coming down the engine firewall. I never owned a Audi. Wouldn't even purchase one.
look for antifreeze coming out of the radiator as the engine warms up after a cold start.
The PVC valve is located on the engine side cover near the firewall on the passanger side of the engine. Coyote John
Is it WATER or Antifreeze ? If it's WATER then it is coming out of the A/C box. It is condensation and that is normal. If it's antifreeze Then it is coming from the engine and I need to know what engine you have to help on that part.
Internal engine antifreeze leak what else could cause besides headgasket? there is no antifreeze in the oil it is clean
it should be close to the fan in the front of the evap case. passanger side firewall engine compartment
from top passanger side under the intake manifold you can feel it.From underside it's ontop of the axels near the firewall.