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What is a Diesel Particulate Filter?

July 9, 2016

What is a Diesel Particulate Filter?


If you’re looking to buy a new diesel car, it will come with a Diesel Particulate Filter . In 2009, European laws mandated that diesel cars must be outfitted with a diesel particulate filter (DPF) for environmental benefits. Though it is no doubt an eco-friendly solution, a clogged DPF has become a source of expensive repairs for drivers.


What exactly does a DPF do?


A diesel particulate filter traps exhaust soot particles. Soot particles have a diameter of 2.5 micrometers or less. Their extremely small size and toxic composition means that they can easily travel deep into people’s lungs, causing asthma, bronchitis, heart disease and other illnesses.

DPF traps soot particles caused by the compression-ignition combustion process, preventing the emission of harmful smoke into the atmosphere.


Does it mean that the DPF gets clogged with soot?


Yes, as with any filter, your diesel car’s DPF will accumulate the soot it traps. But it will heat the residue, convert it into ash, and expel it. This occurs every 500 km or so when the Engine Control Unit raises exhaust temperatures artificially in a process known as regeneration.


Does all the soot get expelled as ash?


Here’s the problem. During short journeys, or in stop/start traffic, the Engine Control Unit may not get time to fully complete regeneration. It causes a partial blockage in the DPF, and the orange warning light in your dashboard will flash/turn on. If you ignore the light and continue driving slowly or through stop-and-go traffic, the engine will start losing power and eventually stop.


What to do when the warning light comes on?


When the warning light starts flashing, change your driving strategy. Move to driving on a faster road, such as a motorway or dual carriageway. Maintain a steady high pace for ten minutes or so. This will prompt the diesel particulate filter to switch to regeneration mode and burn off soot, thereby preventing blockage.


Should you go to an auto centre?


If the DPF does not regenerate and the warning light comes on repeatedly, a trip to the auto centre will become necessary. Auto service technicians will check if the pressure sensors are working properly; remove the filter and replace it with a change-over filter; use ultrasound cleaning to clean the filter or replace the filter with a new DPF filter.


The point of installing diesel particulate filter in diesel cars is to meet the increasingly stringent emission legislation. By attempting to remove your car’s DPF and reprogramming your engine software – as suggested by some websites will adversely impact your car’s roadworthiness and invalidate your warranty.

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