Recently Audi A6 has had several error messages appear once I'm driving.

No answer, similar problem. I know with absolute certainty that the right rear light works exactly as it should, and i have seen no evidence that the adaptive light system is defective. The only difference (2006 Audi A6 Quattro 3.2) is that I have no TPMS light, I have no TPMS light, but the "key not in car" light comes on. I have no time limit, but all of the forgoing warnings are intermittent, some more than others.