after replacing, do you need to relearn with a tech 2 or will it eventually relearn on its own..... i have heard you don't have to relearn and after driving it will be fine...thoughts on this

The way I take it is if you replace you need a Tech2 and how it relearns is like Post #7 http://www.dieselplace.com/forum/showthread.php?t=383508&highlight=vane+position+sensor

I don't know the "official" answer but I changed mine on the road a couple of months ago without a Tech 2 and it seems fine. Scanning vane position and target vane position with EFI look correct. My idle vane position, boost and modified turbo brake vane positions all work as they did before the position sensor failure.