hi all, well let me clear this by saying that I do not have the owners manual of my car (A6 2000 Quattro 2.8) and I am an Audi noob, so this might be easily explained.
so. this warning light showed up 2 days ago, it is yellow and is kind of circule shaped i will try to post some pics of it. i have tried to find a manual online and find out myself but there is not anywhere. Please help me. bunch of thanks...

 

pretty sure that means brake pads.

 

+1 to Jeffla

And when you replace it - buy new pads ready for sensor

 

Two half circles are brake pads getting low. Only the fronts have the sensor. Unless it was a yellow circle with ABS in it -- that ain't good.

 

hey thanks guys for the info, i had to go out of town for work and i had to put aside all my stuff,,, anyways now that i got back i took the car to a shop and you were right, thanks a lot...