14 cascadia. 4 codes. Nox, poor def, derate

Given the age of your truck, the catalyst in the SCR part of the One-Box is probably worn out.
That’s all the exact codes I got last spring on mine. Eventually the dealer installed new injectors and a new One-Box, fortunately in my case I still had factory Extended Warranty.
Expect $14,000 bill to replace it.

 

The "Death Codes" 1 box time. Sorry.

 

Did you findout the issue?

 

Use pittsburgh power max mileage $140 for a half gallon made my code go away use 1oz per 25 gallons of fuel it makes exhaust burn hotter through the dpf, I have lower soot levels even less regens now. The stuff works I promise. And keeps nox levels better. I replaced every sensor and light was still on. Heard about this stuff and I will never stop using it. No more code

 

Told you what is going on. I deal with this on almost a daily basis. I sympathize with you because of the repair cost, but it does not change the diagnosis.

 

What Do you guys think of the 400HP engines

 

Spend $140 on a half gallon of that MaX Mileage . It will slowly clean the aftertreatment. I'm ordering a gallon this time for $220 should last a long time and it will pay for itself it actually gives a little better fuel MPG. I live by this stuff now. I replaced every sensor and still had the codes. Used that Max mileage and the code cleared on it's own the next day