I've had the same problem, been driving like that for more than a year, with check engine light coming on and off but no limp mode,was advised by two mechanics to change the dpf but I didn't feel like it was right, and finally my friend who is also a car mechanic told me to check the differential pressure sensor hosing. One of the hoses was completely clogged, once I've unblocked it no check vsc or p2002 and now the car regenerate on its own, mpg also went up, I hope it'll help to solve your problem. The sensor is in the back of the engine bay little bit on the left with two rubber hoses connected to the sensor and to the steel pipes going to the dpf. Ps. Sorry for my English.