The purpose of this device is to collect all the burnt particles and with a chemical reaction turn them into Co2 which then exits your vehicle from the exhaust. For this chemical reaction to take place the filter has to reach an extremely high temperature, sometimes up to 700 degrees celsius and it can only reach the required temperature if it's driven for long enough.
Best practice is if your vehicle has completed lots of small journeys recently, take the vehicle out for a 30 minute run at motorway speeds. This will give the DPF the time it needs to complete a regeneration. Within the last couple of years Petrol vehicles have been fitted with Gasoline Particular Filters which work in the exact same way and need the same usage to keep them running correctly. If you have any concerns of questions in either area please get in touch and we will be more than happy to help.