I had the same problem, I did the retrofit nav a few months ago and it was showing 0 under the wheel sensor. Over the weekend a I reloacated pin11 wire ( brown wire with the red stripe) to position No10 and now it shows wheel sensor ( number increases as the speed goes up). Search the forum and you will find instructions how to do it. Look under articles/ navigation retrofit addendum information. We are talking about the bordeaux connector that plugs into the back of your mk4 dvd drive.