Reoccurring DEF problem - Freightliner 2013 DD15

I know what is the problem. Ready to pay $500 ?

 

He means if you're ready to kiss Def system bye bye for $$$. This subject can't be discussed on here

 

I mean I know what is the problem. I will not suggest him DPF/SCR delete.

 

My bad, however I don't mind deletes, no hard feelings though

 

1. DEF pump bladder has not enough air or over pressured.
2. Inlet NOX sensor is slow / shows lower value (most likely fault)
3. Engine has 650k plus miles 1 box could be bad.
4. Outlet NOX sensors slow /shows higher value
5.Def pump sucks air while vehicle in motion ( vary rare problem but happens).
The truck was in the dealer and I am sure they have done DEF quantity test and it was ok. Sometimes during parked regen or SCR performance test NOX conversion is ok but when you drive the truck 4364 code pops up. I had similar situations many times and fixed by replacing one of NOX sensors...

 

^^^^ He's correct. Drifting (intermittent) bad outlet Nox sensor is the usual cause for 4364. Have to have patience and watch the laptop screen the whole time during the regen and that bad sensor value will start jumping around. Have to pay attention because it will often go back to normal numbers.

 

Completely agree, just want to add.

1: have seen this once, proper amount of nitrogen can make a difference.
2: this is the most common problem found in the fleet I woork on. The tech needs to know to watch for the spike in the beginning, and also what numbers they should register when they level out ( trouble shooting doesn’t give these numbers).
3; the only times I’ve seen the onebox (SCR side) fail is when soot has passed the DPF filters and coated the SCR. If there’s black in your stack this could be possible. Last check a one box (with help of fleet pricing and “help” from Detroit) was $7000 plus labor.
4: re-read #2
5:i’ve Never seen this, but I do believe it.

One more thing I want to add to the list. I have seen a couple times a buildup of crystallized DEF at the injector in the one-box and the injector tip plugged off and not spraying.
Tip of the day,

If you suspect a bad onebox, and you have any engine warranty left, get an injector to fail before you take it in to the shop, if an warrantable engine issue (injector) fails and craters the one-box, warranty will pay for it.

 

Thanks for additions.
about #3. in 80% cases no need to replace 1 box if it is soot coated. Just install new dpfs, let outlet nox sensor sniff air and drive 10000 miles. )))) put back NOX outlet sensor and you will be surprised. Fixed more than 5 units.