Been doing short journeys lately and noticed that the car has been reving at 1k rpm. The problem usually goes away. But had an issue today where it said on the dash that I had a DPF fault and that i need to refer to the manual. The DPF light together with a light that looks like an exclamation mark inside a triangle is switched on. The DPF light has never been on prior to this so was wondering what is the best thing to do?