2013 Maxxforce 11 white exhaust smoke

My maxxforce 13 does the same and it's normal. If you run NED while driving and your truck is in passive regen you'll see that doser injector is in "inactive" mode but you will see white to grayish smoke coming out for a bit. That smoke is a mostly mix of unburnt fuel and ash. When my passive regen is done the soot level is in the range 20-25 percent but it goes down as I continue driving while blowing whitish smoke for few minutes however the soot level keeps on dropping to low teens or high single digits. If your passive regens do complete your doc is doing its job (you can observe its behavior while driving and doing passive regen, Temps at around 1100 f are the sign of properly working doser injector and doc, I would recommend to run NED during driving if behavior is questionable)

I think you may be dealing with partially clogged dpf which may need baking session if not done for some time.

 

The white/greyish smoke is a sign the DOC isn't oxidizing all the fuel during a regen. It's the early sign of a degrading DOC. Regens normally finish around 10-20 %. They never run down to zero. A sign of a plugged DPF is when your regen finishes and literally 10 mins later the soot load is right back up to 80% again while on the highway.