Been reading alot of forums over the years and a common problem that seems to reoccur is block washer jets. So cause most A8/S8 have headlight ones as well I thought I'd share the one tip that works every time regardless of make or model of car,
Its really simple all you have to do is dissolve a calgon tablet in some hot water and pour that into the washer jet fluid bottle. leave for approx 10 mins and try your washers. Will work every time.
Saves alot time removing wheel arch covers to get to the washer bottle pump and trying to trace the washer lines. And is totally safe so can be done at winter service time even if jets are not blocked. Prevention is better than cure