Forester (SJ) Diesel – Defects incandescent candle

Hello together, since May these years I drive my first Subaru and am totally enthusiastic about the vehicle above all about the interaction of the diesel engine with the CVT transmission. Now there is unfortunately the first problem, an obviously not quite functioning glow plug acc. error code (P066C). The yellow engine control lamp lights up and the error messages in the display say: a) The exhaust cleaning system must be checked b) The starting aid must be checked. According to the friendly one, all this is connected with the fact that modern diesel engines require the glow plugs not only during the start process, but also in certain driving conditions to reduce the soot. As far as OK, everything is on guarantee, however, there is only a date towards the end of next week. Now to my actual question the friendly one could not answer either: Will the DPF Regeneration is still carried out when so many functions connected with the motor control are switched off? Are consequential damage to fear? Many greetings frankx63