17 Cascadia my Def light is blinking & check engine light is on

Discussion in 'Freightliner Forum' started by Oldschooltrucker2016, Oct 15, 2021.

  1. Oldschooltrucker2016

    Oldschooltrucker2016 Bobtail Member

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    Oct 15, 2021
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    I have a 2016 cascadia evolution and my Def light is blinking and check engine light is on also truck won't go over to 55 mph can anyone help
     
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  3. Brandt

    Brandt Road Train Member

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    The computer it limiting truck speed and probably power so you go to get the DEF problem fixed. I think you can go 500 miles before it limits truck to 5MPH.

    Something is wrong with DEF system. I had 2011 truck that did that. It stared as Bad DEF quality. It could be bad sensor or something else.
     
  4. Antinomian

    Antinomian Road Train Member

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    Watered down DEF can cause a DEF derate. A bad NOX sensor can cause it. Also, a cracked DPF filter can do it. There are no doubt other possible causes as well.

    This is one reason I recommend buying the DDDL software and the NextIQ interface. A forced regen will sometimes clear the bad quality DEF code so you aren't derated, even if you haven't fixed anything yet. It might derate again during the next driving regen, but you'll get down the road until then. With DDDL you can also set the parameters that determine what happens during a derate. You can't stop a derate from happening altogether, but you can change the derate speeds from 55/45/5 to something like 95/94/93. That way you just get the blinking light until you fix the problem. There is also a derate acceleration limit that defaults to 0.5 kph per second (2016 Cascadia DD15). You can set that to 100 or something so you don't feel it.
     
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  5. Scoot 1971

    Scoot 1971 Light Load Member

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    I have a 17' Cascadia with DD15 and once had the exact same thing happen after a dpf cleaning. The truck went maybe 10 miles at 55 then derated to 5 mph. Had to get towed to Amarillo Freightliner shop . Shop informed me dpf sensor had failed probably due to dpf cleaning.
    Apparently Detroit doesn't recommend dpf cleaning only replacing filter.
     
  6. Scoot 1971

    Scoot 1971 Light Load Member

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    Nov 22, 2018
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    Yes, it was my def light that was on along with amber engine light.
     
  7. Antinomian

    Antinomian Road Train Member

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    It's safer to swap your filters for a pair of reman filters because it avoids the risk of having your filters crack during cleaning. Detroit takes the risk instead of you. It costs of course. Cleaning is only about $400. Remans cost about $1100 plus another grand for a core charge. On the other hand, if they break during cleaning you're out the $400, plus over two grand for a set of remans that you have no cores to exchange for.
     
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