Dd15 won't complete regen

Needs to be removed and cleaned or replaced.

 

Yes, the DPF filter. Has it even been cleaned? How many miles since cleaning? Many say clean 200 -400k miles.
"Pressure pipes look clear." Blow through the pipe to make sure it is clean and not plugged.
In the other thread you commented in, High Soot Level DD15, read post #5.

 

What is the actual code?
Have you followed the troubleshooting steps?

 

What does the DOC inlet pressure max out at during a regen?
What year is your truck and engine?
What does the error code page look like? Let's see all the codes.

My first guess would be that it's simply time to do a DPF cleaning. How long has it been? There is a page in the DDDL software that will tell you the percent filled the filter is. It's under the Actions drop down. I prefer just replacing the filters with reman filters from the dealer instead of risking having one crack during cleaning.