I'm not.making excuses for the shop, but it might be a part they are out of currently. There are so many fault codes with the emission systems that can be temporarily cleared by forcing a regen.
I have had def doser problems, def tank pump problems, filters needing to be cleaned, NOX sensors needing replaced, etc and they just do a forced regen in the situations where it will keep the truck running for a little longer.
I empathize with @kevin11 , It always makes my heart sink when I see that derate message. The shop may tell you how to bypass it if it leaves you on the shoulder. Different trucks have different ways to bypass the derate.
I have had def doser problems, def tank pump problems, filters needing to be cleaned, NOX sensors needing replaced, etc and they just do a forced regen in the situations where it will keep the truck running for a little longer.
I empathize with @kevin11 , It always makes my heart sink when I see that derate message. The shop may tell you how to bypass it if it leaves you on the shoulder. Different trucks have different ways to bypass the derate.