Understood, but was curious what they found since they also did the TSB.

I had my exhaust assembly replaced years ago by the dealership because of a leak, and they reused the sensors (one they didn't seat the plug completely). However, my truck had a lot fewer miles on it than the OP's.

 

The only one replaced was the one in the tail pipe which was replaced maybe 500 miles prior replacement of the DPF.

 

Same issue with my truck(2011 DRW 90,000mi) Light tailpipe soot but runs great. No codes thrown at all. Dealer says it’s normal for tailpipe to have soot. Been running it like this for a few years now. Sounds like cracked DPF. But why no CEL?

 

you wont get a cel until it reaches a certain threshold of failure. I little grayish maybe normal because of the regen process.

If you take you 90K mile truck on the road for a trip of towing what do the pipes look like then?

How far apart are the regen cycles?

 

Pipes stay the same even on trips to Florida with the camper on. Regens at about 300 -350 miles

I clean them occasionally but they soot up in a couple hundred miles. I’m the original owner. Been running Valvoline Premium Blue 05w-40 synthetic oil since1st year. Also Opti Lube additive.