Haven't had a problem with leaks thus far - I have 6,633 miles on my 911S.

When washing it, I don't use a pressure washer, only a gentle but heavy stream of water from a special hoze nozzle (bought it at Griot's Garage). If you have a sunroof, are you sure it's closed properly? I would think there might be some sort of noise alert if it weren't closed, but I am not sure.

Jim