It has two lights. Pots/Pans flashes a count, Normal Wash flashes a count, and the pair is the message — one then five is a drain problem, two then two is a fill problem. Machines built before 26 May 2010 do not even do that: they mark an X under a row of cycle lights, and the pattern of X marks is the code. The date on the serial plate decides which table applies.
This matters because a good deal of what is published elsewhere about this appliance is invented. There is no “error code 15” on a Viking dishwasher. There is no number at all. Counting the two lights before the machine is switched off is the whole diagnosis, and it is free.