[wowchad]

9 times out of 10 it's exhaust sensors. Pisser is they only replace the 1 bad one and there are 4 total.
I now carry a cheap code reader, spare exhaust sensor & 13mm (-I think 13mm) so I can swap them out on our 6.7L
They did a recall on them, but only on emergency vehicles.
Sure sucks when you drop 60k + on a new truck! but they'll get you up & rolling soon I'm sure.
Please post back what the issue was.