If you regularly make longer journeys then your DPF should regenerate in the natural course of driving, but if this is not the case then we would recommend taking a drive in order to give your DPF an opportunity to perform a regeneration. The exact requirements can vary depending on your specific vehicle, but generally speaking the car needs to be up to temperature with at least a quarter tank of fuel and be driven at a steady speed and throttle for 20 minutes or more, ideally at 2000rpm or more, which is likely to be easiest on a motorway.

The recommend 20 minutes is not a strict time period, but if you do need to brake or decelerate then we would suggest trying again - three periods of 15 minutes in a hour's drive is better than one, as the car may be part way through a regeneration which is stopped when you brake, but resumes when you are at a steady speed and throttle again.