My 2015 had/has corroded plugs from the ecm on down. Dealerships replaced all kinds of stuff until they found the issue and on 2014-15 ecodiesels its bad. Oh they replaced the tcu and def tank…..also the fuel filter housing for no reason. Keep an eye on the wiring harness.
My 2015 had most of those issues as well. It ended up being corroded wires starting at the ecm and subsequent plugs thereafter. They charged me $1200 to replace four plugs and clean up the wires. Lasted almost a year and now another service def error communication error which will be more bad...