2012 Cascadia with 280K Multiple fault codes Please Advise

Once you get caught up on the emissions maint you will be good to go down the road and makeing money.

 

Dont clean the dpf till you find out the problem. Could be just a sensor.

 

If it sat awhile with low def I'm not sure but I think it can crystallize a bit which may be causing your issue .. It may actually go away after the def fluid runs through the system for a bit .. If it's not de rating badly I'd put some more miles on it before spending a pile on money

 

That little tiny flashing yellow led on the def gauge on my last truck meant that it was actually run out of def fluid. It's a tattletale. I could only clear it by hooking up Diagnostic Link and reset the fault codes.

 

spn 5246 15 means you have an active 25% derate for ignoring a DEF error or NoX conversion error, 16 is the same but now at a 40% derate.
spn 4364 is as it says. Could be caused by a number of items, look under fmi 18 in this Detroit page:
https://ddcsn-ddc.freightliner.com/cps/rde/xbcr/ddcsn/808-14.pdf

 

Aside from cycling the key, do you have a battery cut off switch on the truck, if so, shut it off for 15 minutes of so when parked, every once in a while we will have a glitch show up, disconnecting power allows the computer to reset and go back to default, most times, it really isn't anything that is a big deal.

 

This info may help. I would be willing to bet this is the cause of almost all issues with these engines/trucks.

http://rawze.com/forums/showthread.php?tid=33

 

Nox conversion effeiency means your going below 70% efficiency.

This can be cause by contaminated Def, bad metering unit, Def buildup, or a bad one box (not likely due to Low miles)

Check your Def fluid, make sure there's no coolant in there. You can pull out one of the filters and make sure that there isn't a bunch of Def buildup below the doser inside the one box.

Have you taken it to a shop yet?