If you repost with the actual VADIS code it will be easier to help you. That said, my hunch is the canister shutoff valve for the evaporative emission system. This valve is located next to the evap canister, over the rear axle. To access you must drop or revove the rear portion of the exaust system, as well as the heat shield over the rear muffler. With the heat shield out of the way, you can access the valve, but space is tight and removing the clamps and hoses is difficult.