I was working on a 2016 eco diesel, 75k miles stuck in limp mode due to regen plugged soot collector. I found that if I reset the check engine lite then turned the ignition off for 3-4 minutes, fired it back up it would be out of limp mode and would start the regen process. It did go back into limp mode 4 additional times. Each reset process, (reset, turn off wait and restart) I was able to get further down the road, and it eventually completed regen. Running great now. I noticed that with the a forced regen process with my friend's snap-on unit, the vehicle wouldn't regen, but it also said to turn off ignition for at least 60 seconds. So I tried this process with my Harbor Freight unit and it worked. It's worth a try if you're stuck in plugged soot collector regen limp mode.