4364 fmi 18 over snd over

Discussion in 'International Forum' started by Twista89, Jan 24, 2022.

  1. Twista89

    Twista89 Light Load Member

    85
    38
    Oct 2, 2017
    0
    Hello,

    I have a prostar with the n13 motor and hsve been dealing with the 4364 fmi 18 code for the last 3 months which caused other codes to pop up.

    Things replaced
    Inlet nox sensor
    Dpf
    Air control valve
    Doc replsced 6 months ago
    both cleaned
    Exhaust back pressure valve

    can an exhaust manifold leak cause this code as the tech mentioned there might be an exhaust leak on 6 but they never pursued it any Further.

    this code popped up in flagstaff az And this isn’t the first time it happened over here and I’ve read post about flagstaff being a problem for them and this code as well on Detroit motors. It also loves to pop up on Monday’s and then go away after the truck does successful regens.

    any help would be appreciated before I go find a non def truck.
     
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  3. Heavyd

    Heavyd Road Train Member

    7,374
    5,672
    Feb 4, 2009
    0
    This code is for low Nox conversion detected. What this means is the ECM had detected that the outlet NOx is too high and the SCR hasn't been reducing the NOx enough. This can be caused by a few different things. First thing to check is your DEF injector and lines to make sure that are no leaks, and perform a spray test. Injector is removed from the Decomp pipe and with NED software, it will run a spray test into a container where you measure how much DEF is sprayed out. A good injector will spray out 100 ml during the test. If that is good, then remove the Decomp pipe and SCR to inspect for plugging and clean as needed. If all that is ok, then I fear your SCR itself is degraded and no longer working to convert the NOx to water, CO2 and N2. SCR do not last forever and do wear out.
     
  4. ChuckMartel

    ChuckMartel Light Load Member

    148
    89
    Jan 22, 2021
    0
    I really hope you didn’t replace all those things just for that code….
     
    Heavyd Thanks this.
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