2017 peter 579 with MX13 has max derate over def.

Discussion in 'Peterbilt Forum' started by Arctic_fox, Apr 28, 2021.

  1. Arctic_fox

    Arctic_fox Medium Load Member

    Sep 16, 2016
    So bit of background so you understand the question. Truck just had both nox sensors repaired. Got about 2000 miles and then it threw a bad def code. Drained tanks and replaced with new def and error self cleared. Drove 500 more miles added def and it came back with max 5mph derate. Managed to limp it to a ma and pa shop where they drained and filled def again. Tried a regen truck was non responsive to their laptop. So they pulled in a sister shop who had a davie4 dealer laptop and when he tried it was billowing grey smoke. So he hooked up his laptop and it gave him this

    and this


    Basically they found my output nox sensor was fried again and no signal from sensor also doser was non responsive reading 0.00 pressure on davie 4.

    They pulled doser and found this. Output was basically concrete so it was replaced along with nox sensor.


    Ma and pa shops tool now works and it no longer billows grey smoke however one of the sensors on the SCR is now non responsive and SCR is showing 60% full. Still non clearable max derate.

    My question is if there is anything else i should check before i pay to have a wrecker pull me to a dealer and have the SCR replaced? Would rather avoid paying for a $5500 part if there is something else it is likely to be.

    Much apprecated for the help.
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