When DEF equipped trucks are in active regeneration is it harmful to shut down the engine? My 2016 2500 goes into regen occasionally. I only know its doing it because instantaneous mpgs drop, and I smell the odors others have mentioned. The tailpipe on shutdown is hotter then H***. This morning coming to work it was regenerating for the last 15 miles. I shut down and could smell the burnt rubber smell. Will it go back into regen when I re-start this afternoon. TIA