Welcome!
I wouldn't be surprised on any outcome pertaining to the EPA. Although, for FCA, what happen with VW really set the standard, so I'm sure if they did cheat they are trying to get on the best graces possible.
Picture of the plug in this thread:
http://www.ecodieselram.com/forum/threads/transmission-shuts-down-running-in-rain.1169/#post-9401
It's just a shot in the dark from my end since you mentioned snow storm and maybe, just maybe a bad connection was left open to the extreme elements.
Really hard to say without the actual code # that's stored.
Some have had problems with the harness that runs into the transmission coming lose and/or the connection just not good.
Welcome to the forum!
Perhaps some good news!
http://www.greencarreports.com/news/1108598_2017-ram-jeep-diesels-should-be-certified-by-epa-shortly-company-says
http://www.freep.com/story/money/cars/chrysler/2017/01/26/marchionne-fiat-chrysler-epa-diesels/97079320/
Anyone else come across this? They do mention the EPA allegations in this video starting around the 3:30 mark.
The MPG figures are about what I expected...