DPF systems

DPF stands for Diesel Particulate Filter. Fitted to many modern diesel-powered vehicles, the filter is designed to remove particles of soot (mainly carbon) from a vehicle's exhaust and is fitted by manufacturers to help reach targets for exhaust emissions. The DPF consists of a physical filter, which is fitted within the exhaust system of a car or commercial vehicle, usually relatively close to the engine. DPF systems are now fitted to virtually all vehicles sold and used within Europe and if your car or commercial was fitted with a DPF from new, it must be retailed, as removal will result in an immediate MOT test failure.

There are a variety of DPF systems in production, using mostly cordierite, silicon carbide, ceramics or metal fibres. However, all have the common aspect that unlike catalytic converters, diesel particulate filters involve 'forcing' the exhaust gas through the filter material. This process is inherently inefficient and results in a small loss of performance and increase in fuel consumption. However, the most common problem with filters is that over time, they become blocked with carbon deposits. This can happen relatively quickly, especially in the case of vehicles used in cities or other areas with a large degree of low-speed driving. DPF units are designed to be able to be 'regenerated' in normal use. This involves heating the unit to a temperature high enough to burn off excessive carbon and this is usually accomplished by driving the vehicle relatively fast for some time. Normally, this means in excess of 5o miles per hour for ten minutes, so invariably, this means a motorway or dual-carriageway journey. If regeneration is not carried out as soon as required, the filter may become permanently damaged and the entire unit will require replacement. The filter units themselves are usually costly and worse, if a problem is left for too long, serious engine damage can result.

Recently, there has been a great deal of debate with regard to whether the filters are actually effective or not. Soot particles are the result of incomplete combustion, however, improved engine management systems and high-quality diesel fuels enable most vehicles to meet the relevant emissions standards without the need for a DPF system. The units are costly and add to weight and complexity, and it is undoubtedly true that performance and fuel economy are worsened by their use. Ironically, this becomes even more true in view of the requirement to drive relatively fast for some distance on a regular basis. Part of the issue is that vehicle manufacturers need to produce and sell vehicles across a wide range of markets, where fuel quality may differ substantially. As production and supply may often be diverted from one market to another, the DPF system is a cost-effective measure for manufacturers, allowing less-stringent and accurate engine management settings. Nevertheless, the latest technology is a great deal more efficient than it was originally and DPF systems are here to stay. In view of current legislation, they are also now a legal requirement if fitted from new.

In the vast majority of cases, and certainly for vehicles used in the UK and most of Europe, we can help if you encounter problems with your DPF system. We have the correct equipment to correctly diagnose any fault (which may not necessarily be with the filter itself). in the event of any problem, we can carry out proper regeneration on site. Even if the unit is completely blocked, we can send it away for professional cleaning or repair, saving you potentially a significant amount of money. Even in the absolute worst-case scenario, we can source replacements that meet all required standards for a lower price. If you have a warning light illuminated that suggests a problem with the DPF system, please contact us for assistance. It is absolutely vital not to ignore any such warning, as serious damage can quite quickly occur otherwise.

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