Fog light grilles first
You could take the fog light grilles off first as you can access the bottom of the headlight washer mechanism this way.
Obviously it depends where the leak is, but i have had 2- one of the was where the t piece join is, which is on the drivers side and can be seen through the fog light grille, the other was on the passenger side where the pipe joined the mechanism. Blth were loose connections and simply pushed/cliped back in place.
Both cold have been fixed through the fog grilles if i had actually looked before pulling the bumper off. If you havent seen the pipe efore to know what to look for, its black corrugated stuff, about 8mm diameter
Otherwise, limoncello has described the process to remove the bumper, the only thing i would add is have a helper so it doesnt drop on the floor and use a cloth on the floor too so you dont scrape the paint.
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2004 A8 3.0 TDI Sport Brilliant Black - now gone
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