I keep getting a P0685 on my Audi A6, i was told possibly relay circuit open for a gnd for the fuel pump. The Launch X431 Diagun will not start at all.
Car is a 2003 A6 3.0 quattro.

i think fault code giving you that fuel pump relay is faulty.trie new pump relay from vw/audi 15/20 pounds.common fault on range.good luck

 

You can Google the codes as they are standard across the OBD range for all vehicle manufacturers. Your code indicates a relay issue with the power to the ECU. These relays sometimes have two separate relays inside. One side supplies power to the ECU the other controls the fuel pump. If either sides isn't working, the car will not start. Pop in the new relay when it comes and see if that doesn't fix the issue.