On the Mk2 you open the "Central Electrics" controller and get the current coding, it'll probably be coded as 04096 and you need to add 8 to it so basically it becomes 04104,however it only works with the factory fit towbar so I'm going to run a light up to the console and fit it in the blank.Again that code is for a Mk 2 dont know the code for a mk1 but worth noting the reading and trying the 8.I bought the Vag-Com from fleabay with drivers but still had problems.Now found that Vag-tacho is better but its 200 euros.It does more esp if you need to adjust the mileage for any reason or add 2 stage locking,miles to empty etc.But they aint worth what is virtually