DD13 recurring code SPN 4364 FMI 18

[aaronb]

I bought a Cascadia with a DD13 a few months back. Every week or two I keep getting the SPN 4364 FMI 18 code. It only seems to come on when loaded heavy, pulling a grade or in a hard wind and when it’s cold. The first time I had it come on I went to a shop and they changed the NOX sensor. The second time I went they were going to change a sensor until I told them it had a new one. They said they did three regens including a low temp regeneration, because things weren’t looking quite right on the diagnostic computer. They charged me 825 dollars for the regens. After that I just bought a handheld I can check and clear codes and do forced regens. I clear that code out when it comes up. I’m just curious if anyone knows what could be the problem. If I don’t stop and clear it right away it goes into historical codes and not current. The light on the dash has to be shut off every time with the computer. It stays on even if the code isn’t active. The dealer said the DPF might need cleaned and is causing the code. Thanks for any help you might give.