DEF led blinking. At 25% Derate.

My KW did that type of scenario about 2 years ago.
Took it into cummins.
They said filters were clogged and would have to be cleaned and baked. About a two day turn around.
Second time it did it 7 months later, the particulate filter had to be replaced.
The sys tem works well, but cummins said the filters clog up faster because of all the crap that the bio diesel leaves behind.

 

I go to Cali every week and like clockwork at the NM line the yellow light comes on the doser has crystallized . so I stop take my rubber mallet and give the valves and electronics on top of the DEF TANK a few whacks . it'll Regen driving down the highway . works every time . at least until I get in and have doser valve washed . my trucks a 2016 freightliner Cascadia

 

It hasn't failed me yet . it came on at Guymon Oklahoma last night it went off this morning around Santa Rosa Nm

 

Bumping this old thread because I'm having this exact same problem and not sure what to do. I was running a load from Pleasant Prairie, WI to Braselton, GA when both amber MILs came on and the DEF light began blinking. Engine derated to 55mph. Now this happened in Atlanta during a weekday so hitting 55mph wasn't even possible and it didn't even delay me much (last DEF fill-up was less than 200mi back, Pilot in Monteagle, TN). While I was swapping trailers at my customer, I believe the truck shut off a few times and the CHECK light and DEF light disappeared, restoring my speed. Nevertheless, I put the truck in the shop at my company's Atlanta terminal for a due B service and mentioned the DEF problem. They did not go in detail what they did other than disconnecting some stuff and checking for clogs.

Next load was from Fairburn, GA to University Park, IL. Made it about 600 miles to Neoga, IL when all the lights returned and the engine derated again. Got the truck to a tiny truck stop in Mattoon-Charleston area and called my ERS for help. I was told to finish the load (another 148 miles) and take it to a Freightliner maintenance garage not far from my customer. Here's hoping I get answers.

 

Their is a DEF filter that's supposed to be changed