SPN 4374 FMI 14 code on a 2017 Cascadia with DD15

Discussion in 'Freightliner Forum' started by AlexD13, Sep 8, 2021.

  1. AlexD13

    AlexD13 Light Load Member

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    Jun 13, 2016
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    Hello everyone, wondering if anyone has gotten this code or has an idea what it can be? SPN 4374 FMI 14. I have a 2017 Cascadia DD15 with 600k miles
     
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  3. QUALITYTRUCK

    QUALITYTRUCK Road Train Member

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    romulus,mi
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    9 times out of 10 it is a failed DEF pump. Before you replace remove and inspect/replace DEF pump filter.
     
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  4. AlexD13

    AlexD13 Light Load Member

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    Should I change the lines as well if it is the Pump?
     
  5. SWM_TECH

    SWM_TECH Light Load Member

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    Apr 15, 2018
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    Here's the diagnostic steps for the fault.
     

    Attached Files:

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  6. Ross_Tech

    Ross_Tech Light Load Member

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    Aug 31, 2021
    Michigan
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    Before you condemn the pump, check the pressure at the doser with a manual gauge. The pressure sensor is in the doser, and I've seen a truck where techs changed the pump twice, only to find out the sensor in the doser failed.
     
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  7. AlexD13

    AlexD13 Light Load Member

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    Jun 13, 2016
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    Mechanic so far said there is an Air leak causing this , he wanted to fix that before changing a pump
     
  8. ABiceRoads

    ABiceRoads Bobtail Member

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    Apr 30, 2018
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    Mine is leaking from the fitting where it connects to the def pump. I found a small clamp on this fitting is broken and loosing def pressure. Code I got is SPN 4374 FMI 14. My question is Can I just replace small plastic clamp on this fitting to stop the leak or do I have to replace the hole heater line?
    Any suggestion will be greatly appreciated.
     

    Attached Files:

  9. QUALITYTRUCK

    QUALITYTRUCK Road Train Member

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    romulus,mi
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    Unfortunately you need to replace the heater line.
     
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