2012 Cascadia DD15 Codes

Yes, the Input measure NOX going in, the Output measure it going out, computer calculates "NOX Efficiency" and if not enough it starts throwing codes. For one little thing like that you pay all this money for DEF, the SCR system, and all the repairs that go with it. It seems to be the most trouble prone and expensive system in the emissions burdened modern engines.

 

DPF has nothing at all to do with NOX problem, that is in the SCR / DEF system completely separate. Plans are to ramp up enforcement now of emissions system 'fixes'. Drivers, carriers, and shops that do work can have huge fines.

 

I would be curious to know how they can tell besides seeing soot on the tail pipe which can be a residue from a failed DPF in the past. I don't think they are able to remove the filters and inspect anything and even if they did i expect them to buy new seals and required clamps and put everything back into its original location.