ok so i search here and even yahoo answers, couldn't seem to find the answer to my problem, my b6 '02 a4 rear view mirror stopped auto dimming for the past week or so. It used to dim every headlight that appears in the rear view mirror to aqua green color but lately i noticed that it completely stopped. I read on the manual that the dimmer will only work correctly w/ the sun shade down or if the rear windshield is clean. My car doesn't come w/ the pop up shades in the back, and it's been raining a lot lately in my town so theirs some tiny dry water spots on the rear windshield but that's about it. So i wiped the rear windshield w/ a wet towel around the middle area of the rear windshield inside n out, auto dim still doesn't work... anyone got a solution to this? thanks.

edit:
the whole rear view mirror is practically spotless and so r the front and back sensors. But the front sensor is a slight off to the side of its mold it's fitted into, no leakage from fluid or discoloring like the other posters wrote, i'm thinking either it just plain broke out of the blue or maybe dust or something is preventing it from working