AdBlue & DPF
DPF
How to clean a DPF filter?
CheckFuelPrices Editorial
Expert Written • 4 industry sources
A blocked DPF can be cleaned in three ways: passive regeneration on a long motorway run, active regeneration triggered by the engine management system, or a forced regeneration carried out by a garage. Choosing the right method depends on how blocked the filter is and how long the warning light has been on.
Passive Regeneration: The Free Fix
How it works:
Passive regeneration happens automatically when exhaust temperatures exceed around 600°C — typically during a sustained motorway run at 60–70 mph for 30–50 minutes.
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When to try it first:
If the DPF warning light has only just appeared, a 30-minute motorway drive at a consistent speed is the first thing to attempt before spending money at a garage.
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Why short journeys cause blockages:
Stop-start town driving keeps exhaust temperatures too low for regeneration to occur, which is the most common cause of DPF blockages in urban diesel vehicles.
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Active and Forced Regeneration
Active regeneration:
When soot load reaches around 45%, the engine management system automatically injects extra fuel to raise exhaust temperature and burn off the soot — this can take 5–10 minutes.
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Forced regeneration at a garage:
If the DPF is heavily blocked, a mechanic can connect diagnostic equipment to initiate a forced regeneration cycle, which typically costs £80–£150 and takes under an hour.
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Do not ignore a solid DPF warning light:
A flashing or solid DPF light means regeneration has failed. Continued driving risks permanent filter damage and a bill of £1,000–£3,000 for a replacement DPF.
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DPF Cleaning Additives
Fuel additive cleaners:
DPF cleaning additives are poured into the fuel tank and lower the combustion temperature required for regeneration, helping passive regen occur on shorter journeys.
Off-vehicle chemical cleaning:
For severe blockages, specialist workshops can remove the DPF and clean it with pressurised chemical solutions — this costs £150–£400 and is cheaper than full replacement.
Avoid DPF removal:
Removing a DPF entirely is illegal under the Road Vehicles (Construction and Use) Regulations and will result in an automatic MOT failure.
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Preventing Future Blockages
Use the right diesel:
Using quality diesel and ensuring the engine reaches full operating temperature on most journeys will significantly reduce the rate at which soot accumulates in the DPF.
Consider whether diesel is right for your driving:
If most of your journeys are under 10 miles in urban areas, a diesel vehicle with a DPF will block repeatedly regardless of maintenance. A petrol or hybrid may be a better fit.
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Check fuel prices before filling up:
Running a diesel well means filling regularly with quality fuel — CheckFuelPrices shows live diesel prices at 4,000+ UK stations so you can find the best price near you.
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Sources
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