Exhaust emission regulations have required diesel powered cars to be fitted with a diesel particulate filter, or DPF, since 2009, with the aim of reducing the sooty particulates in cars exhaust emissions. Though these devices are effective in their aim, you may find your driving style causing problems as sooty deposits build up and potentially clog the filter.
The DPF needs to periodically burn off the sooty deposits in a process called regeneration and if this is not working properly, you may find the DPF warning light coming on as the filter becomes full and blocks the exhaust. There are two kinds of regeneration, passive and active. Passive regeneration of the DPF occurs at high exhaust temperatures, such as during motorway driving at high speeds. Obviously, cars that only do small journeys and stop start driving such as on many commutes, these high temperatures may never be reached. To counter this many cars feature active regeneration, where the cars ECU increases fuel to the engine to increase exhaust temperatures, however, this may not work if certain criteria aren’t met.
Ignoring the DPF warning light could see you visiting a garage to have the filter cleaned or even replaced. To counter these problems its important to take your car to higher engine speeds from time to time to burn off the deposits in the filter, especially if you seldom reach high speeds. Remember, cars fitted with a 6th gear may not reach adequate revs even at 70mph, so consider using a lower gear occasionally.