3719 code can only be cleared with a service regen initiated through Service Advisor, or possibly might require a DPF Recovery procedure through Service Advisor.
That code by itself is the end result, so something else is is causing the DPF to plug up.
Is the exhaust system setup in the monitor for automatic regens? If it is disabled that could be a cause. Does the operator shut it down when regen starts? A leaking injector or dosing injector, lots of idle time or low load running, low engine operating temperature are some of the things that can cause the DPF to plug.
There are 3 DPF soot load readings in Service Advisor that can help determine issues and whether the DPF needs to come out to be cleaned.
If it does not or cannot complete a regen, and there are no other codes, then there are 4 tests that will need to be done:
1. Regeneration Abort Source Identification Test
2. Exhaust Temperature Management Test
3. Fuel Dosing System Air Purge Test
4. Fuel Dosing Pump Diagnostic Test
These all can only be performed with Service Advisor.
So, basically, you now need the dealer to take over, or an independent who has Service Advisor.