Cascadia DD13 and DD15 SPN 3720 FMI 15 DPF ASH CLEAN REQUEST

This fault code is actually very simple, it simply means the the DPF filters inside the One Box have reached their limit and require maintenance. They must be removed, inspected, baked and cleaned.
Detroit recommends to have the DPF filters exchanged with new or Reman, this of course would make the cost go up. But you always have the option of have the DPF filters baked and cleaned.
Once the filters are cleaned and ready, it does require:
2 NEW EXHAUST CLAMPS Part Number DDE A0004902241.
10 clips
10 bolts or screws
I personally prefer to remove the complete One Box from the truck, this allows for easier access to the DPF filters.
You will need the DDDL software in order to input the DPF serial numbers and reset the fault code.