I'm in the middle of the countdown condition and about 85 miles away from being limited to 4mph. Service Exhaust Fluid System is the only message. No DTC's, no check engine light. Truck is in middle of a regen, which it started with only 10g of soot on the meter. Had the DEF heater replaced today, that cleared the P21DD and P20B9 codes that were in it, added some DEF then regen started. Drove 25 miles to help it, did nothing.

https://www.techconnectcanada.com/bl...t-fluid-basics

That link scares the $#!+ out of me, looks like it knows I had a tune (mild, fuel efficiency based one) and it's out for revenge. I loved the tune but had to go back to stock as Mass Inspections are brutal now and more states are going that way. I'll keep up with this thread to let others know how I make out.

Anyone with any ideas, it would be greatly appreciated.
Thanks
Jesse