“Why Not Just Take The DPF Off?”

Drivers frustrated with regular DPF problems may be tempted to remove the filter entirely. This is encouraged by the many firms advertising DPF removal or ‘DPF Delete’ services quite openly on the web. They sometimes claim that it is not illegal to remove the DPF, and that the vehicle will still pass MOT smoke opacity tests without it. These are however, half-truths.

Although it may not be illegal for companies to carry out DPF removal work, the vehicle owner is left in a somewhat unfortunate position. This is because the vehicle is rendered illegal to drive on public roads (although it may be acceptable to use niche situations such as track racing). The law states that it is an offence under the Road Vehicles (Construction & Use) Regulations (Regulation 61a (3)) to use a vehicle which has been modified in such a way that it no longer complies with the air pollutant emissions standards that it was designed to meet. DPF removal will almost inevitably result in this requirement being broken. The Department for Transport has issued guidance clarifying this.

Emissions tests carried out as part of a standard MOT are not currently sensitive enough to show whether a DPF is fitted. It is therefore irrelevant that a smoke opacity test may be passed without one; DPFs are designed to produce much cleaner exhaust emissions than that. However, since February 2014, a visual check of the exhaust system has been required as part of the MOT test and if a DPF should be fitted but is found missing, this will result in automatic failure.

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