Yesternight my car's [Y reg 406, 2.0L, 110 HDI] check engine light lit up and it gave antipollution fault, 2 minutes after me starting her up to go home from work.
I read few topics already posted about this fault on site mention that owner's car has gone into limp mode.
Mine isn't. She is still revving and with fault I hit 120 mph thinking it might be slightly clogged DPF and it might clear it out.

Any idea what could it be?
I don't know if it was a temporary issue that occurred for few seconds and then went away, but the fault code is still appearing, or something permanent. I started her today just to check if it is in limp mode but it wasn't. She is driving great just ever.
Would really appreciate some help and advice. Thanks!