I have a 99 A6 2.8 and the battery went flat after a few weeks lack of use. When I tried starting it almost turned over a couple of times but ended up just getting the clicking sound of the starter motor. I charged the battery fully and the car started fine. Except the speed and rpm gauges dont work,the lights on the dashboard digital display only come on intermittently, and when removing the ignition key an audible alarm similar to the lights being left on alarm comes on and stays on for a minute or two. Have I cooked something? Is this an ECU fault? Anyone know how to reset things?

 

Audi A6 1.8T 98 R plate AEB 20 valve engine 40,800 miles.The Actual ECU diagnostic priority message with no reported faults but the Air con digital temp displays for NS/OS started flashing when turned on and continues for 4 mins. This problem does not appear to effect the A/C operation although it is too cold to check the freeze/compressor function.

 

I would disconnect the battery for a few minutes to reset the computer, and see if the problem persists. Make sure you have radio codes handy if yours has theft prevention built in.