Sporadic no power 2.0D DPF

Hello Volvo driver, now my elk has unfortunately also caught it, for 3 days he has been ticking around. When starting the engine everything is still ok, then about 4km drive with normal performance unfolding and then the elk does not take any more food, Dehzahl only up to 2000U/min and max 110km/h……but all this without an error message and only when the temperature meter has crawled on the first line of the display. ch then immediately new start is all over and everything runs like before, the ignition doesn’t have to leave out even 2 seconds. I had the whole thing now 5 times and it went off every time without an error message or something like that, it may be due to the weather, is now in the monemt zeimlich wet with us and just so at the freeze point…….I my water break in a sensor plug or something? Have just just got the 60000km view behind me and was up until now actually quite lucky h with the car. Does someone have a good tip for me or do I just have to change the agr valve 😉 Thank you very much! the moose hunter