Regen failure need advise

Stop truck Set brakes turn off cruise and push button opposite way .. One way starts regen the other way inhibits it .. Hopefully mechanic did the proper welding procedure or took dpf off to weld it preferably a lot of sensors can get messed up from welding .. Other than that you may need to clean dpf if its getting plugged so quick

 

If it won't regen, there's some condition which is causing it. If there are any active faults which trip either engine light, it won't regen.
If the ECU senses that the clutch or accelerator pedal are at a position greater than zero, it won't regen. Happens to me often when I have to do forced regens, and is usually rectified by tapping up on those pedals, unless there's a bad sensor switch.
Also, when you take off a DPF to clean it, the outlet needs to be inspected, as well... 2012 model year will be an SCR truck, which means you'll have a three piece DPF system (inlet/DOC, DPF, and outlet)... whenever you remove a DPF, ALWAYS clean and inspect the DOC, as well... if the DOC is plugged from soot, there's a good chance you have either excess flow or a steady leak coming from your dosing injector, and that'll have to be replaced. If the DOC is cracked, that'll plug it.
Not sure what model of KW you have, but the SCR trucks with the three piece DPF assembly have an outlet which typically angles up at a 90 degree angle, and connects to a crossover pipe which goes to the DEF dosing unit... those outlets are prone to cracking right at the base of the neck, and this allows ambient air in, which throws off system temperatures, and causes the ECU to register a faulty conversion efficiency rating with the DOC and/or SCR.
The aftertreatment differential pressure sensor may also be giving a faulty reading, which will throw codes. The SCR mechanical system might be out of calibration... which, if recurring, means you'll be replacing an SCR. The DEF doser could be out of whack.
Some fault codes will read out on the dash, some will simply tell you to hook up a diagnostic tool.
Before he tried doing the regen, did he go to the "Advanced ECM Data" menu, then go to "Aftertreatment Maintenance" and reset the aftertreatment system before he cleared codes? Also, did he go to the "Features and Parameters" menu (I'm assuming you have a Cummins, in which case, the program would be Insite) and look under "Switches" to ensure that the clutch pedal position and accelerator position switches were shown as being disengaged?

 

Is their any updated news with the regen issues?? Curious if you got the bugs worked out?