Reoccurring DEF problem - Freightliner 2013 DD15

Yes sensor drift does look like my issue. It can take over 20 minutes for my outlet NOx readings to settle into numbers that make sense.
Some mechanics said on the forums they have seen it go up to forty minutes.

 

I’ve had these same codes and replaced the outlet nox sensor. It got 90% nox conversion. The problem came back when I had a heavy load going up a long hill. It derated to 55 after awhile then came out of derate and lights went out. Could it be inlet sensor also? Previously I changed def pump and filter and def injector and put awning kit.

 

Stop idling your engine, you'll be amazed at the results!

 

could be 100 things, included bed inlet sensor, bad 1 box, tight valves, overspraying injectors,...

 

I’ve replaced both sensors and harness. Replaced doser, supply lines, pump and filter, installed awning kit. I only use blue def. Still same problem when going up steep hills. Spent 8k so far. Have had this problem since I bought the truck 8 months ago. In shop, it gets 90% conversion rate. What could be the problem???

 

Bad one box. Maybe a crack or something, replacing one box is next step. Or let the nox outlet sensor "breath fresh air", problem solved

 

Mine turned out to be an exhaust leak. Exhaust manifold gaskets.

 

I gotta same problem just bought 2016 freightliner cascadia.Can you help me please?

 

What is the problem?