Reoccurring DEF problem - Freightliner 2013 DD15

I just loaded and fired the parts cannon at one truck yesterday that actual dosing wasn’t near requested. We replaced the DEF pump and the injector. I wasn’t able to talk to the tech that watched the regen after the repair. I’ll talk to him this morning about it.

 

It didn’t change the difference between actual and requested. I was hopeful when I took the old pump and injector apart and saw the computer circuits, but no change. We’ll see if by chance it has any effect on the intermittent SCR efficiency code, but It’s doubtful.

We’ve already put 2 inlet and outlet NOX sensors in in the last 6 months, I can’t believe they could be bad??

 

I looked everywhere to find any helpful info.. But I’m thinking it’s a ACM problem. Emissions =Nightmares

 

it's not ecm problem .
what kind of helpful info you are looking for ?

 

It’s very strange that in the last 1 month or so.. every truck that pull in the shop for Aftertreatment problem DDDL shows that real DEF dosing is like x3 more than requested.. so I assume that we have problem with our diagnostic tools.. Any help/advaice?

 

remove def hose from atd and run parked regen. monitor nox values. go to dealer and ask them that for SS 1023350 document. its about drifting nox sensors. Read it careful. You will see what can cause sensors to drift . every epa10 1 box will show this issue after 650k miles. Mine is doing same ####. I have 900k m now. my scr is bad.

 

I think he’s talking about the difference between actual and requested DEF dosing, not the NOX values.

Have you noticed this??

 

yes. actual dosing is related to nox values. if everything is ok in 1-box requested and actual values are close. During parked regen it must be 800-900 .

 

do you have access to DTNA Solution ? if yes go to there and look for SS 1023350 . it's about drifting sensors at high temperature and bad harness that can cause drifting values.

 

Finally found it. There’s not a lot of info there... I did pick up some things while I was searching.

There was a bulletin from back in 16 about remapping the fuel. For humid conditions.

So, this week we replaced the largest harness (ACM out) on one of the units with the reoccurring issues. Our thinking is that we messed something up just enough when we replaced the clutch. Which would follow along with the document you suggested. I didn’t get to watch the regen so I’m not sure if it corrected the deviation with the dosing.

If this doesn’t fix it on this unit, There’s only a few more things we can replace. The ACM, the 3 month old NOX sensor, or the One Box.