[xtac1080]

Hello diesel guys. I'm not much on diesel repair and one of my trucks keeps going into limp mode from what I imagine is a clogged DPF filter. I've posted the DTC list below. The truck is a 2015 Freightliner M2 106 with the Cummins 6.7 ISB engine & 60k miles. It doesn't see much highway time so I try to run a stationary regen every few months. I ran the SCR test and it failed on the SCR Catalyst test. I'm not sure where to begin aside from pulling the filter and cleaning it. I've smoked the exhaust & intake for leaks and couldn't find any, couldn't find any DPF fluid leaks, and the DPF fluid checked out with a refractometer. My driver did tell me the truck exhaust has been smelling funny over the past few weeks. Any thoughts on where to begin troubleshooting? 

I'm about ready to delete the DPF system all together.