We’re sometimes asked by customers to remove Diesel Particulate Filters, or DPF for short. Your DPF is designed to make diesel cars run as cleanly as possible with current technology, though cars often used for short journeys can become blocked, due to the way the system regenerates and cleans itself. Until recently, it was perfectly legal to remove a blocked DPF. The car would run adequately without it, though with an increase in soot particle emissions. However, many people are unaware that a change to MOT regulations in February 2014 now includes a physical check for the presence of the filter. If the car was fitted with one when new, it must be present. While your diesel car may perform fine without it, you will not be able to pass an MOT test without it in place. DPF cleaning is a better way to stay driving.

Example of catalytic converter failure

So what is the best way to ensure your Diesel Particulate Filter continues to perform well and not become blocked? Understanding how the system works is a start, as many drivers are unaware of them. The filter works by trapping soot particles that occur during normal diesel operation, trapping the most harmful elements. Eventually if course, the filter will become full and need emptying. This normally occurs during a session of high temperature running and for most people this isn’t a problem. However, if you use your car for a lot of city driving, this doesn’t occur and crs used for stop-start driving are vulnerable to the DPF filter becoming blocked. Often the first you know of it is reduced performance and a red warning light.

To avoid this, head for the open road on a regular basis and give your diesel car some good exercise. Many large leasing and fleet operators are now including this advice in information sent to fleet drivers, as any remedial work is often not covered under a manufacturers warranty.

In fact, there’s a case for suggesting that city drivers are often better off with a good petrol engine or hybrid, especially when you factor in the reduced cost of petrol at the pumps compared to diesel.