Well, they're full of it.
The p0216 code is ALL THEY NEED to make a claim with Cummins.
Cummins doesn't like paying for these so they usually take their sweet time, dealership calls them and tries to make a claim, Cummins tells them to do all these different tests, dealer does them and calls back, Cummins tells them to do more stuff, they do it... finally Cummins accepts the claim and it takes a few days to ship the part considering the dealership doesn't have one in stock... so on and so forth. Once the part is there it takes them about 6 hours to install (slow and lazy as they usually are).
Just a real pain, if you can, call a few different DC dealers in your area and ask them what they're schedule is, the sooner you get it in there, the sooner they'll be done.
-R. J.