2016 DD15 - 4364 FM18 and 5246 FMI0

Discussion in 'Freightliner Forum' started by Eaglewing, Dec 7, 2022.

  1. Eaglewing

    Eaglewing Bobtail Member

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    Dec 7, 2022
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    Hi all,

    I have a 2016 DD15 with 693k miles. Last night she lit up like a Christmas tree; displaying the following two codes and message:

    SPN 4364 FMI 18
    SPN5246 FMI 0
    engine derage 25%
    DEF Quality poor, Check DEF

    Red Stop Engine light Was on as well, DEF light was blinking but couldn’t force regen.

    truck limited me to 5mph

    I cleaned out the DEF injector, which had DEF build up, and placed it back, still didn’t change. Called Loves over to me, and the technician said everything looked good in the computer but he couldn't clear the codes. I saw a truck shops near me and started heading over, but as I was driving 5 mph, I started going downhill and got to about 40 mph, at which point there was a loud noise underneath the truck and the lights all disappeared, and the truck began to gain speed. I’m on my way to delivery right now, late but thankful that I didn’t have to get towed.

    Anyone have any idea what it could be?

    3 months ago I took it to Freightliner because it kept forcing me to regen and I had the check engine lights on, they found large building up in the mixing chamber and performed a DEF awning. Set me back $3k. The truck ran for a bit but then started giving me the check engine lights and derating the truck. I thought maybe it’s the DPF filters, so At about 685k I changed the two DPF filters because the truck kept having to regen, about 3 weeks ago. It worked just fine the past two weeks.

    this time, I’m driving through VA with about 40k lbs in the trailer, and the truck was fighting up the hills before it sedated and all the lights came on.

    Any ideas as to what the problem could be?
     
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  3. SWM_TECH

    SWM_TECH Light Load Member

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    Apr 15, 2018
    0
    SPN4364/FMI18 "SCR NOx Conversion Efficiency Low"
    Worst case is a failed 1-box! But you need to test for cheaper causes of the fault.
    Like contaminated DEF, improper concentration of urea in the DEF, biased Nox sensors, excessive DEF build up in in the SCR mixing chamber, over temperature in aftertreatment system, improper DPF maintenance.
    Any air management faults, EGR faults and fuel system faults should be fixed first.
    Probably not practical to solve yourself without Diagnostic Link. I am seeing about 32 steps in diagnostic process to solve this fault. I would recommend you going to a reputable truck repair shop that works on Detroit Diesel engines.
     
  4. uncleal13

    uncleal13 Road Train Member

    3,560
    5,645
    Apr 9, 2009
    Humboldt, Sk
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    Yes that’s the early signs of a worn out One-Box, right number of miles too.
    It’s more likely to happen when the engine is working hard, such as climbing hills.
     
  5. Antinomian

    Antinomian Road Train Member

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    2,538
    Feb 17, 2013
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    The dealership had to have it apart to install the awning. Also, the OP said he had the DPF's changed. They should have seen evidence of any burn through or if the DOC's were pushed in.

    Sounds more like a bad NOX sensor to me, but it will take watching a regen with DDDL to find out.
     
  6. Eaglewing

    Eaglewing Bobtail Member

    3
    0
    Dec 7, 2022
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    Like Antinomian said, when they installed the DEF awning they had to remove the DPF filters and look at the DOC as well. When I replaced the DPF filters myself two months later (the truck sat for about a month after they installed the DEF awning), the DOC filters looked like they were in good condition (pictures attached below for reference).
     

    Attached Files:

  7. Eaglewing

    Eaglewing Bobtail Member

    3
    0
    Dec 7, 2022
    0
    I changed the DPF filters myself, you can look at the DOCs in the images I'm attaching below. I ended up replacing the DEF Metering unit (AKA DEF doser, DEF injector) on the side of my Onebox as well, and replaced my DEF filter with a new one. The old one (pictures of old DEF filter attached) looked like absolute crap, which makes me believe the previous owner never serviced the DEF Filter.

    Attached you can see my old DEF metering unit/doser and the port on the one box with DEF leakage.
     

    Attached Files:

  8. Antinomian

    Antinomian Road Train Member

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    Feb 17, 2013
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    The DDDL software has a procedure for testing the flow rate of the DEF pump. If both the doser and the filter were clogged the pump might be weak now. Also, the line from the DEF pump to the doser is heated. Sometimes the heater coil fails. And as I said before, it could be a bad NOX sensor.

    Running a regen while monitoring with DDDL is the best way to find clues.

    Keep an eye out for soot marks by the vent slots on the one box housing. If you don't get the DPF filters sealed properly then you can have poor NOX conversion, which can cause the poor DEF quality code.
     
    Last edited: Dec 30, 2022
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  9. uncleal13

    uncleal13 Road Train Member

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    Apr 9, 2009
    Humboldt, Sk
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    The DOC can “look” good, but the catalyst still wears out rendering them ineffective.
     
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