This is the second time in less than two years that we've had the same problem with our 2002 A6 2.4. The sequence of events goes like this:

1. Battery drains, car won't start
2. Batter replaced, everything seems to be OK
3. Less than a week later, a buzzing noise can be heard from back seat area
4. Shortly afterwards, the instrument cluster fails - first FUSE message pops up above odometer. Then battery indicator drops to zero,clock display and all other digital displaysstop working
5. When the car is turned off, the radio stays on and has to be switched off manually
6. Date/time display always resets itself to 00:00 and 01/01/2000 when car is started up
7. When I filled up at the petrol station, it took 30 minutes for the display to show "570km" (of fuel remaining)

There is no effect on the actual performance of the car. It drives fine, but this is the second time the same thing has happened! I'm not keen on spending $1000 again to replace the entire instrument cluster like the first time, and then have it happen again in 18 months. Any clue as to what could be triggering this sequence of events?

Thanks!

 

It almost sounds like theres some kind of short that is taking out the cluster, but two years seems like a long time for it to be ok. Any idea whats buzzing. Nothing really pops in my head when i think buzzing from that area. That might be the cause of your short.