I have a 2015 Mack MP7 that I cannot get out of a DEF 5 mph derate. It originally came in for CEL which was P103C00 - NOX Efficiency Inducement, SCR Unit, P113712 - Oil Thermostat Short to Battery, P24F700 - A/T Fuel Air Purge Valve Stuck Closed, P269800 - A/T... Login to read more.