Code 3364 and 3521 came on my truck out the blue

Discussion in 'Trucks [ Eighteen Wheelers ]' started by DAX_, Sep 26, 2021.

  1. DAX_

    DAX_ Medium Load Member

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    Filled up def at flying j in Dallas on Thursday


    Today(Sunday) I fill up on diesel again at pilot in Decatur Illinois

    About 30 minutes later I see my check engine light is on(not flashing on solid) and my low def warning light is on

    I look on the dash and that fault code number (3364) comes on, saying exactly 'After treatment diesel exhaust fluid quality - abnormal rate of change '

    Then as I'm typing this thread fault code 3521 comes on saying "conditions exist"

    I'm running heavy, 45,000 pounds and have a 2020 freightliner so there is no regen button or regen override for me to press. The only thing I have is the regen I can click from the dashboard screen but that does not work


    Any help
     
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  3. Daytrck

    Daytrck Bobtail Member

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    I’m new to trucking. I had a similar DEF problem totally different truck but I hear def problems run similar in most cases. I spent over $3000 looking for the issue and found out that it was just the filter pad at the bottom of the tank had gone bad and was clogging the lines. Try checking under the truck if it’s possible where the DEF is injected sometimes you can take that apart and wash it with a bit of water if it’s crusted or clogged to clear it and can keep you going for a bit or until it gets clogged again.
    If it persist you may want to drain the tank and see if there is any debris in the tank. I’ve heard from most mechanics that getting DEF from the pump isn’t good because you can sometimes pick up a lot of debris and transfer them to your tank. It’s better to buy the box knowing that what you’re pouring in is pure and clear.
     
    DAX_ Thanks this.
  4. DAX_

    DAX_ Medium Load Member

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    Update

    So last night as I get to the receiver my low def light starts flashing and I get a message that truck will now begin to derate at 5mph

    However the truck never derated at all.

    I make it to a mechanic but right before I get there all the lights and messages on the dash go away except for one which is the ECM 3521 saying DEF Fluid Property Conditions Exist

    The guys at the shop hook it up to a little computer and he tells me all the fault codes are inactive and that it won't shut me down.

    He also says that since everything is inactive they more than likely won't find anything wrong with it if they start working on

    Should I keep driving or take it to another shop
     
  5. dunchues

    dunchues Medium Load Member

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    From my experiences it's probably not a real problem but more than likely a bad harness or weakening connection that's fooling the ecm. It can still lead to engine management taking over but if the condition isn't active they can't diagnose the fault. I'd wait till it lights up again ( and I bet it will ) before you throw parts at it that are likely ok.
     
    DAX_ Thanks this.
  6. DAX_

    DAX_ Medium Load Member

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    Would a freightliner dealer be able to diagnose it even without the lights being on?

    What if I take a pictures of the codes on the dash and show them
     
  7. dunchues

    dunchues Medium Load Member

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    They'll be able to see the inactive codes but there's no path to diagnose the problem, code has to be active so they can follow the steps to find the right fix.
     
  8. Diesel Dave

    Diesel Dave Last Few of the OUTLAWS

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    It’s a 2020, don’t you have a Warranty on it still ?
     
  9. DAX_

    DAX_ Medium Load Member

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    Yes
     
  10. DAX_

    DAX_ Medium Load Member

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    So do I just keep driving until im stranded lol
     
  11. dunchues

    dunchues Medium Load Member

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    If the codes aren't active you can't get to the root of the problem and all you can do is throw parts. Don't shoot the messenger, I don't care what you do I'm just explaining if the lights aren't on you can't properly fix it.
     
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