I also noticed the truck was not raising the temperature. Than I kind of got lazy and stopped cleaning doser valve than truck started asking for parked regan all the time. I would remove Doser Valve every 2-3 months and gave it a nice cleaning and truck was running fine. When I had my 2012 Prostar with maxxforce engine first two years were ok, while most people were complaining about regan issues shockingly I did not have those issues.