Diesel Particulate filters (DPF) or 'traps' do just that, they catch bits of soot in the exhaust.
As with any filter, they have to be emptied regularly to maintain performance. For a DPF this process is called 'regeneration' . The process of regeneration, is when the soot is burnt off at very high temperatures, to leave a tiny ash residue. Regeneration may be either passive or active.
Passive regeneration takes place usually when you drive on the motorway for example. The exhaust temperature gets so high, that it automatically carries this out, without you even knowing its happening. Unfortunately, many cars don't get this sort of use, or if they do, not as often. This is when the ECU (Engine management unit) takes control and carries out an 'Active regeneration'.
Many journeys and driving conditions these days are stop/start. With this kind of driving, regeneration may not be completed and this is when a warning light illuminates, to show that the DPF is partially blocked. When the soot level reaches a set limit, the ECU will make some adjustments in order for the exhaust temperature to increase. You should be able to complete the regeneration by driving the vehicle for at least 10 minutes, or at low gears/high revs. If you choose to ignore the warning light, over time the soot level will increase, and most likely cause more problems. At this stage it will need to be taken in for repairs or a forced regeneration. You should never leave it to chance, considering a new DPF could cost you about £1000.
Reducing diesel soot emissions by 80%
Changes to new car emissions legislation scheduled for 2009, the so-called 'Euro 5' standards, will make particulate filters as commonplace in diesel car exhausts as are catalytic convertors on petrol cars.
The goal is an 80% reduction in diesel particulate (soot) emissions but the technology's not without problems – many cars are already having the particulate filter warning light illuminated (which indicates a partial blockage).
It's clear that changes to driving style may be required too for maximum benefit from these systems.
If you have a DPF warning light appear, you should immediately arrange to have it checked out, before you end up with huge repair costs.
Here at Speedwell Garage, we have invested in the technology to enable us to carry out forced regeneration processing on most cars. Contact us today for further details.
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