Is it legal to remove a DPF?

No. Removing the DPF is illegal on public roads in the UK under the Road Vehicles (Construction and Use) Regulations. The MOT test visually checks for a DPF on vehicles that should have one fitted — removal causes an automatic failure.

Can I use a DPF cleaning additive?

Fuel-borne DPF additives lower the soot combustion temperature, helping light regeneration in vehicles with marginal exhaust temperatures. They are a maintenance aid rather than a cure for a fully blocked filter.

What engine oil should I use on a DPF-equipped diesel?

Always use a low-SAPS (low sulphated ash, phosphorus, sulphur) oil meeting the ACEA C specification or the manufacturer's specific grade. Standard oils produce ash deposits that permanently block the DPF substrate.

How long does a DPF last?

A properly maintained DPF typically lasts 100,000 to 150,000 miles. Premature failure is almost always caused by incorrect oil, short-journey use, or an underlying engine fault increasing soot output.

Will a new DPF fix the limp-home mode?

Only if the limp-home was triggered by high DPF back-pressure. After fitting, clear the fault codes, reset the DPF mileage counter if required, and perform a test drive with an extended motorway run to verify active regeneration occurs correctly.

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DPF Filter buying guide — what to know before you buy

The diesel particulate filter — also known as the DPF, soot filter, particulate filter, or FAP filter — captures carbon soot particles from diesel exhaust gases to meet Euro 5 and Euro 6 emission standards. The filter periodically regenerates by burning off accumulated soot at high exhaust temperatures. When regeneration fails repeatedly, the DPF blocks, triggering a warning light, limp-home mode, and ultimately a replacement requirement. CarParts247 stocks OEM and aftermarket DPF filters from Bosal, Walker, and Klarius for a wide range of diesel passenger cars and light commercials.

Why DPFs block

A DPF relies on reaching sufficient exhaust temperature during regeneration to burn off accumulated soot. Vehicles used predominantly on short urban journeys never reach the threshold temperature, preventing successful regeneration. Faulty EGR valves, injectors, or turbochargers that increase soot loading also accelerate DPF blocking.

Short-journey driving that prevents active regeneration
Faulty glow plugs preventing cold-start combustion quality
EGR valve stuck open recirculating excessive soot into the intake
Using the wrong engine oil — must be low-SAPS for DPF-equipped vehicles
Ignoring early DPF warning lights that indicate partial blockage before full failure

Forced regeneration versus cleaning versus replacement

A partially blocked DPF can often be cleared by a forced regeneration performed with a diagnostic tool, or by an extended motorway drive that sustains exhaust temperatures above 550 °C. Professional DPF cleaning (pressure-flushing with specialist fluid) is an option for heavily loaded but structurally sound filters. Replacement is necessary when the filter substrate is cracked or its soot-loading cannot be reduced by any regeneration method.

Always diagnose and fix the underlying cause of DPF failure before fitting a new filter — a new DPF will block just as quickly if the EGR, injectors, or driving pattern are unchanged.

Fitting a replacement DPF

Replace the associated differential pressure sensor at the same time — it may have been damaged or contaminated by the failed DPF. Ensure all soot is cleared from the upstream pipes before fitting. Programme the new DPF data (mileage counter reset) into the ECU using a diagnostic tool where the vehicle requires this.