Cascadia DD15 and DD13 fault code SPN 4364 FMI 18. SCR NOx efficiency low

Typical fault code with Freightliner Cascadia One Box, possible causes:
1) Bad DEF quality
2) Bad DEF metering unit
3) Bad or faulty NOx inlet or outlet sensor
4) Bad after treatment harness
5) Bad ACM (aftertreatment control module)
6) Bad DPF
7) Bad One Box
Troubleshooting this fault codes can be time consuming, always begin with looking at all other fault codes (Active and non active). Here is the history behind this truck, both NOx inlet and NOx outlet sensors have been replaced less than a year ago due to NOx fault codes. Truck goes from LA to New Jersey every week. Knowing the history of the truck is just as important as repairing it.
Perform a parked regen and in order to check pressure, temperatures, diesel doser function, DEF dosing and then NOx efficiency.

[@SmooothShifter]

There are so many variables with this. Before y'all start tossing harnesses, dosing valves, awning kits, and other stuff at it - look at the simple things. My 2016 DD13 just threw the code standalone yesterday. Reman one box 3 years ago, 290,000 on the filters. I also had an EGR cooler fail and she was huffing coolant, which probably didn't help the particulate filters any. Replaced the cooler last November. My truck hasn't called for a parked regen in quite some time, so it's doing its passives. I threw the laptop on it, and I didn't have any surrounding codes - just low NOx efficiency. I did a burn and the numbers were good. A parked regen will clear any DEF buildup. IMO, the awning kits are just a band-aid over bad basic habits. We've been having some major air quality issues in the Northeast with the Canadian wildfires. People wearing N45 masks with the particulate count in the air - it was hard to breathe in NYC a couple of days ago. My truck is using that air too. Know how many miles are on your one-box filters, and ditto for your engine air filter. I change mine every 6 months. I also don't idle my truck on layovers. I run a Webasto for the cold weather and get by on small fans for the summer months. Idling ( even fast idling ) is the kiss of death for these systems. If the code comes back, I'll stop back and correct myself here. Good video, and informative.

[@DK-fq3hy]

hi Carlos! I own an EPA10 as well. blowing with compressed air extensively the DPF and DOC then reset the ash meter will extremely help the truck. Also, using motorkote is important.

[@Troymatti]

Too many issues was mentioned for 1 code this def system is BS , good job bro

[@TATEXPRESSINC]

Great job on the video👍🏻

[@MrConstant1]

Excellent video. This is really good info. Thank you for sharing.

[@jesusnunez3583]

Carlos eres el número uno !!!

[@CarlosDieselElectric]

Gracias

[@dieselmobiletruck1631]

Mrs pedro fuentes I have 2014 freightliner 114sd with a dd13 after 20 minutes of the regeneración as starter the nox combertion drops gradually to 40 %

[@carlosrivas1097]

Something i see is the outlet temp higher than inlet. I believe it should be lower

[@localfreight4222]

Can u please make a video about how to do and engine fuel pressure test on Detroit engine dd platform

[@namentatic4978]

That regen DPF temperature needs to be above 1000F. I see there around 800F. Good luck.

[@CarlosDieselElectric]

I agree. This is definitely my least favorite fault code to work on. Things can go from expensive to really expensive real quick.

[@dieselmobiletruck1631]

The temperature goes above 1000 degrees

[@bareqali7169]

Great video bro very informative. Which program do u use and from where I can buy it ? Thanks in advance

[@CarlosDieselElectric]

Thank you, I use the Detroit Diesel Software. I purchased my software from diagosticlink.nexiq.com

[@bareqali7169]

Carlos Diesel Electric thank you 🙏

[@prashanshan7125]

Thanks for posting..!

[@nachoojeda3437]

Thank you for sharing your videos 👍👍👍 can you please tell me what parameter I need to change to enable Cruise control on Freightliner Cascadia DD15

[@amritmattu5024]

Hi i replaced a def doser but when i do a quantity test it wont inject any def even on a new def doser

[@CarlosDieselElectric]

What year is the truck? Need more information

[@amritmattu5024]

2020 cascadia dd15

[@CarlosDieselElectric]

@@amritmattu5024 try running the ADS self check and look at the speed (RPM) of the pump. This is a pass or fail test. Let me know what happens.

[@10junekaran]

Hi I have freightliner cascadia 2014 Detroit dd15 and while driving I had def light blinking and have spn 4363 FMI 18 code, code spn 3364 FMI 2 and 25% derate what is the problem is that onebox that’s what mechanic saying it has low efficiency and outlet Knox sensor was changed by previous owner Diagnosed shows 1- scr nox coversion efficiency very low 2-scr nox conversion efficiency low 3-scr outlet nox sensor -drift 4-regen temperature-out of range low

[@CarlosDieselElectric]

Number 1 and 2 are the same, they are both telling you NOx conversion low or very low. First thing it will tell you is to check DEF quality. In most cases this is not the problem. Number 3 could be a bad NOx outlet sensor, if they have never been replaced then I recommend to replace them both (inlet and outlet). How many miles are on the truck? Number 4 could be the diesel doser injector (located on the outlet side of the turbo) is blocked due to carbon or soot. This is very common on these trucks. When the parked regen is being performed, you need to check the temps on the DOC in DOC out and DPF and also check to see if the diesel doser is opening. This is what allows the One Box to actually start the regen process as the diesel doser begins to spray diesel in towards the One Box. I know this is a lot to take in. What have you done so far?

[@kengerman1014]

I have same code on my 15' 594k miles Where in Montebello are you located? I'm local

[@CashNYC]

that DEF metering unit u guys can pull it down and clean it dealer gonna tell y'all its not a serviceable item bullshit it has filter screens that gets clogged up from bad def or just def crystal save y'all selfs some money fellas.

[@vetodmp2821]

I got SPN-4364 FMI 18 aftertreatment 1 SCR Conversion Efficiency type Constant. I have changed Inlet and outlet, doser valve and about 1 year 5months ago I have changed filter, map sensor is decently new, exhaust pressure same, and I have put 5 new clamps around DPF and SCR. What you think any idea?

[@CarlosDieselElectric]

What year? How many miles?

[@Typicalpunjabis]

If have 2015 freightliner with cummins isx 500. Got same code 4364 with fmi 31. What could be issue?

[@CarlosDieselElectric]

NOx efficiency can be many things. Start with DEF. Use good quality DEF in the box. Could be NOx sensors. Could be bad DPF

[@cristoperodriguezgil8075]

Hey Carlos I just changed both ny knox sensors on my 2015 freight liner so I need to do anything with the computer? I also change the heater lines and the dozer all my sensors and still getting some lights.

[@CarlosDieselElectric]

What fault codes are you getting?

[@cristoperodriguezgil8075]

@@CarlosDieselElectric SPN 5246 fmi 15 n4364 fmi 18

[@carlosrivas1097]

Dealer does sell even the screens in the unit.

[@cristoperodriguezgil8075]

Hello please reply I have a 2015 and I change that valve it looks different on mine but I’m getting this code and I replaced it about 2 months ago what else could I fix.

[@CarlosDieselElectric]

The EPA10 versus the GHG is different, you may need the DEF awning installed. Look up Busted Knuckle by diesel doctor. He has a video that covers the DEF awning. How many miles are on the truck?

[@cristoperodriguezgil8075]

@@CarlosDieselElectric 648000 and I’ve seen it thanks someone mention they change their dpf filter would that help?

[@jorgefacio690]

I replaced the metering unit both nox sensors and I'm still getting spn4364 18. what else can I check?

[@CarlosDieselElectric]

What year?

[@jorgefacio690]

@@CarlosDieselElectric 2013 cascadia with the epa10 system

[@jorgefacio690]

@@CarlosDieselElectric also the one box is about a year old

[@yorsdyvillatoro9280]

Hi Carlos question when the nox conversion is on 0.0000 what's the mean it's bad oh good nox inlet it's on 440 ppm outlet it's on 796

[@CarlosDieselElectric]

That is bad. Most likely a bad sensor or bad One Box. I think a sensor could be bad. Possible outlet

[@yorsdyvillatoro9280]

@@CarlosDieselElectric thanks a lot my man, 👌✌️

[@diesel-landdiagnostic7407]

What did it en up Being? Got the same issue. I replaced outlet nox sensor and still got the same issue.

[@CarlosDieselElectric]

@@diesel-landdiagnostic7407 what year is the truck? How many miles on the truck? Have you replaced NOx inlet and Outlet sensor? What have you done so far?

[@diesel-landdiagnostic7407]

Replace outlet nox sensor, nox conversion is on 0.0000 while inlet is somewhere 460ppm and outlet it’s on 640ishh ppm. And when it’s a on regen mode I hear a noise inside the box.

[@alexismendoza4992]

Hey Carlos my truck has the same issue they just replaced the wire hardness for the def senors and cleaned the filters like 3 weeks ago and now has that code on is there any way to contact you.

[@CarlosDieselElectric]

How many miles?

[@catnlion]

Just got out of the shop 2000 miles ago and having an awning put. This was the only code. DEF quality etc were reported okay. Today it's back. So after days off the road and thousands of dollars do you have any suggeztions?

[@CarlosDieselElectric]

I’ll be honest. This is one of the most difficult fault codes to troubleshoot. You can replace NOx sensors, clean DPF filters, use clean DEF, perform a parked regen, have NOx efficiency above 70% but when you start to drive and the truck does a driving regen, the NOx efficiency will drop below and trigger NOx efficiency fault codes. But before I go any further, how many miles are on the truck? What have you done so far?

[@catnlion]

@@CarlosDieselElectric the truck has 973k miles. In the distant past they have replaced some sensors, cleaned DPF filters etc. They just did the awning. So currently I show no active faults. I did have two the FMI 18 then a FMI 1. The light is still on but again showing no active. BTW this is a 2016 Western Star 5700 XEi 6x2 downspeed DD15. Thank you for your time and help.

[@CarlosDieselElectric]

@@catnlion the codes can come and go depending on what the truck is reading. A software (if needed) may help. Try having the valves adjusted. The SCR efficiency codes can pop up for something simple. Is the One Box original to the truck?

[@catnlion]

@@CarlosDieselElectric yes it is. Considering the mileage things are just now being changed. For example I just did the brakes a couple weeks ago. FYI, the maintenance light went out a few miles ago. Every time I stopped today I looked and had no active faults.

[@CarlosDieselElectric]

@@catnlion then I say keep going. If need be pull over and do a parked regen. But considering you are at that mileage you are doing great. Detroit Diesel say you would typically get about 650K-750K out of One Box.

[@mohanadaldulaimi2687]

Hi what software you use please and from where I can get this software please

[@CarlosDieselElectric]

I use the Detroit Diesel Diagnostic Link, I purchased my software through Diagnosticlink.Nexiq.com

[@christiangaytangarcia692]

I had my truck read and that code came out as well as bad def quality... we were told by a mechanic to swap the def doser injector ... We did and nothing shot out of the doser, I unmounted the doser and observed and still nothing came out, I unhooked the inlet and outlet hoses and we had def fluid coming in from the inlet side, Im thinking its an electrical problem any ideas?

[@CarlosDieselElectric]

What year is the truck?

[@christiangaytangarcia692]

@@CarlosDieselElectric it's a 2016 freightliner cascadia with a dd15 engine

[@christiangaytangarcia692]

@@CarlosDieselElectric is the ecm keeping the doser from turning on might it just need a forced Regen? Or is their a reason it won't turn on...we already swapped the Box sensors....

[@CarlosDieselElectric]

@@christiangaytangarcia692 how many miles? When you are doing a parked regen? What are the temperatures?

[@christiangaytangarcia692]

@@CarlosDieselElectric I do not know the temperatures we had a mechanic come over today he said that he was not receiving a signal back from the dozer or the nox sensors.... I checked the wires going back after I found the schematic to pins 28 and 33 on the ACM 120 pinout over to pins one and two on the dozer plug and I'll check good continuity the mechanic did a reset on the codes and we are able to do a Regen but it does not take the region after completion the light is still blinking I amounted the dozer and it's still not spraying at least not when I have it unmounted but I did see some crystals on the nozzle so I'm assuming it is spraying sometimes any thoughts?

[@alexcorvi2254]

On EPA 10s it’s almost 9 out of 10 times a harness issue if you have circuit codes. Also EPA 10s don’t have a def quality sensor

[@CarlosDieselElectric]

Alex Corvi after this video was done. Truck ran good but I did ultimately replace the after treatment harness. I was saving that for the next video. I usually start with low hanging fruit, being that the truck is very high mileage I started with the DEF metering unit because it is the least expensive thing. The harness is expensive so I prefer to take that route but you are correct in saying the DEF quality sensor isn’t present. But the ACM triggers a fault code for the DEF quality because of the low NOx efficiency.

[@CarlosDieselElectric]

Alex Corvi thanks for sharing. I feel the more information and knowledge is out there the more these trucks can stay in the road.

[@DK-fq3hy]

@@CarlosDieselElectric after treatment harness? Could you please let me know where is it located. Thanks!

[@CarlosDieselElectric]

@@DK-fq3hy All Detroit aftertreatments have an ACM (computer) that works with MCM (engine computer). From the ACM (typically located on the driver side behind the front wheel) you have a harness that runs to the DEF pump, DEF tank, a few other accessories and goes over to the One Box and the One Box sensors. Like Alex mentioned, the harness could be causing the fault codes. It is usually in two sections.

[@skyhighcarrier9981]

Right bro same thing

[@mk360livecom]

Where is your shop located ?

[@larrypryor6616]

2015 cascadia dd15 falt code spm 3223 fmi 7 please help..,...

[@CarlosDieselElectric]

Looks like a NOx sensor Inlet issue (failed to activate), try performing a parked regen and you have to look at the NOx efficiency. It must be above 70%. If you still have the same issue then you may have a harness issue. Start with the parked regen first using your Diagnostic Link Software so you can see temps, voltage and overall performance of the parked regen.

[@larrypryor817]

How can I get the program to do the regn

[@CarlosDieselElectric]

I purchased my program from Diagnostic Link. Nexiq Thievy have two versions available. The standard is the one I use but I will be upgrading to the Pro version. Most people can do most everything with the standard version

[@cabdiraxmanahmed413]

I have this issue in my truck I need to talk to u

[@joshuabrumback9681]

I have a 2016 Cascadia with a dd15. Over the last several months I've gotten a lot of these codes. I've replaced both wiring harnesses, the NOx sensors, DPF filters, ACM, def doser, and def filter kit. We did the long regen that takes hours and got the efficiency to 99% before we cut it off. It cleared all the codes. Then a couple weeks later I got this code while climbing a big hill. I'm also smelling def when pulling these hills now which is new. They are out of ideas. Should I replace this metering unit? The box is a small fortune and honestly I cannot swing the $10k

[@joshuabrumback9681]

Any help would be greatly appreciated.

[@pliniosilva2133]

Have you check if your truck needs or have the “Awning kit” ?? It’s something that goes inside the one box and helps with the def spraying more evenly into the exhaust gases and mixing better.

[@CashNYC]

dude when I bought my truck I use to get this code going up hill I replace both nox inlet and outlet sensors and still going up hill code came back and after awhile it would disappear. I cleaned my def metering unit nothing work.. what fixed my problem for good I got brand "new" Detroit DEF filter for my cascadia. Never seen that code again in 2 years and been up plenty of hill. so buy brand new filters. I paid $2400 my old filters wasn't any good otherwise I would have got $1200 back but no complain. I'm just happy its fixed and i did it all myself. I have a 2012 Cascadia.

[@superfrio05]

Carlos...buen dia..tengo un 2014 freightliner cascadia dd13.. con mismo codigo que hay que cambiar...gracias

[@trustinthelord2248]

@@CashNYC Wzup my guy is u talking about the dpf filter the big once in the one box because I’m having the same problem ever week when I climb a hill

[@JuanPerez-po6bl]

wich diagnostic sofeware are u using

[@CarlosDieselElectric]

Juan Perez I am using the Diagnostic Link Software from Detroit. You can purchase it from Nexiq.

[@thadiesel7655]

Where can I buy the software

[@CarlosDieselElectric]

Check with Nexiq. diagnosticlink.nexiq.com/DTNA/Default.aspx This should take you to where you need to go.

[@jeancadet5862]

I have the same code but I have 2015

[@10junekaran]

Can you help

[@jorgefacio690]

can anyone guess how many times he said AGAIN?

[@CarlosDieselElectric]

Jorge Facio haha. Probably too many times.

[@jorgefacio690]

great video by the way

[@CarlosDieselElectric]

Jorge Facio thank you

[@dynamicdopamine]

@@CarlosDieselElectric again...great video sir.

[@WORM1100]

He still does that to this day, mmk. And again, mmk. Haha. I still watch his videos but they are twice as long as they need to be from repeating himself, mmk. And again, they are twice as long as they need to be.

[@nachoojeda3437]

👍🏽👍🏽👍🏽👍🏽

[@dynamicdopamine]

I need to talk to you

[@CarlosDieselElectric]

Dynamic Dopamine I can help you tomorrow when I get back to work.