The first one (recall 0413000) was issued on a faulty headlight switch. However, Audi technicians could, while trying to repair the switch, improperly install a plastic cover on the driver side crossmember. This could then cause a short if the exposed member touches the headlight switch wiring harness. Audi has not issued a fix at the time of this posting or indicated when it will notify A6 owners of the problem. Contact information can be found at the link if you own one of the cars in question.
[Source: Consumer Affairs]