amitch888 wrote:Is it right that for the 05 and 06 models you need the smart gauge not the scangauge?
Yep! I have both and the Scan Gauge doesn't work in my '05 D4D as they don't have the same OBDII compliance as the newer models, despite having the same plug. I wish the design of the Smart Gauge was more like the Scan Gauge, as its a bit bulky, but I am very happy with mine, especially the adjustable warning lights/alarms.