Buying Guides
Cars With DPF Problems: Which Diesels Are Affected And Should You Buy One?
6 min read
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CarVerified Team
Diesel particulate filters cause the most trouble on diesels that only do short trips. Here's how a DPF works, the warning signs, typical costs, the MOT rules and what to check before you buy.
Almost every diesel car built since around 2009 has a diesel particulate filter (DPF) in the exhaust. It traps soot and burns it off from time to time. When that doesn’t happen, the filter clogs, and a blocked DPF can mean warning lights, limp mode and a big repair bill.
The good news is that DPF problems are mostly about how a car has been driven, not just which model it is. Knowing that tells you which used diesels to avoid, and which can still be a great buy.
Check this car free first: enter the registration at carverified.co.uk to confirm the engine and fuel type, and see the MOT history for emissions failures and mileage.
How Does A DPF Work?
The filter collects soot from the exhaust. To clear it, the car “regenerates” by burning the soot off:
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Passive regeneration happens naturally at sustained higher speeds, such as on a motorway.
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Active regeneration is when the engine’s computer raises the exhaust temperature to burn the soot off. It needs around 15 to 20 minutes of steady driving at higher speeds to finish.
If a car only ever does short, slow trips, regenerations keep getting interrupted and the filter gradually fills up.
Which Cars Are Most Likely To Have DPF Problems?
Diesels Used Mainly For Short Journeys
This is the biggest single factor. A diesel that spent its life on school runs and short town trips is far more likely to have DPF trouble than one that did regular motorway miles.
Small Diesel Superminis And City Cars
Small diesels bought for town driving often never get the longer runs they need. Our main guide to cars to avoid buying covers specific small diesel engines with a reputation for DPF and related problems.
High-Mileage Diesels With Poor Maintenance
A faulty EGR valve, injector or sensor makes the engine produce more soot, which fills the filter faster. Skipped servicing makes this more likely.
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Systems That Use A Fluid Additive
Some diesels, including several Peugeot and Citroën models, use an additive fluid to help the filter regenerate. If the additive runs out, the filter clogs.
Warning Signs Of A DPF Problem
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A DPF warning light on the dashboard.
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The engine management light, or the car going into limp (reduced power) mode.
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The cooling fan running and a higher idle after you switch off, which is a sign it was regenerating, happening very often.
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Poor fuel economy or a burning smell.
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Smoke from the exhaust under acceleration.
How Much Does A DPF Cost To Fix?
These are typical UK ranges that vary by model, so always get a quote:
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Forced regeneration at a garage: often around £100 to £300.
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Professional DPF clean: often a few hundred pounds.
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New DPF: often £1,000 to £3,000 or more, plus fixing whatever caused it to block in the first place.
DPFs And The MOT
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Removing a DPF is illegal on a road car, and the MOT checks for it. A car with its DPF removed or tampered with fails.
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Visible smoke of any colour from the exhaust of a diesel fitted with a DPF is a major fault at the MOT.
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A seller offering a diesel with the “DPF removed for better performance” is selling a car that won’t pass its MOT and may not be insurable.
What To Check Before Buying A Used Diesel
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How the car was used. A low annual mileage on a diesel often means short trips, so ask the seller what the car was used for.
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The MOT history for emissions failures, smoke advisories and the yearly mileage. You can check it free with our MOT check.
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Service history showing regular servicing with the correct low-ash oil, plus records of any DPF cleaning or additive top-ups.
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No warning lights on the dashboard, and none that come back after a test drive.
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A proper test drive that includes at least 15 to 20 minutes at a steady speed, watching for smoke, hesitation or warning lights.
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No signs of tampering. Walk away from anything with the DPF removed or “remapped” to disable it.
Take Our Used Car Checklist To The Viewing
Our free used car checklist builds a tick-off list for the exact car you’re viewing: choose dealer or private seller and petrol, diesel, hybrid or electric, and it adds the extra checks for that fuel type. Pick diesel and it adds the DPF, smoke and emissions checks for you. You can add notes as you go and download it as a PDF.
Should You Still Buy A Diesel?
A diesel still makes sense if you do a lot of motorway or long-distance driving, roughly 12,000 miles a year or more with regular longer runs. If most of your driving is short town trips, a petrol, hybrid or electric car will usually be cheaper and less hassle. Our petrol vs diesel cost calculator can help you compare the running costs.
Which CarVerified Report Covers This?
A history report shows the MOT emissions record, mileage pattern and any write-off or finance against the car, which tell you a lot about how a diesel has been used.
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Free check: start with the free vehicle check for the make, model, engine size, fuel type, year and MOT and tax status, so you can confirm the car matches the advert.
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Silver: the core vehicle history check, including write-off and stolen records. Finance is not part of Silver, but it can be unlocked separately.
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Silver Plus: adds the outstanding finance check.
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Gold: the most complete report, adding ex-taxi, salvage and valuation checks.
See exactly what each report includes on the pricing page or in the sample report.
Frequently Asked Questions
Can You Drive With A Blocked DPF?
You can usually drive a short distance, but don’t ignore the light. A longer drive at a steady speed sometimes clears a partial blockage. If the light stays on, get it checked before it causes further damage.
How Long Does A DPF Last?
Many last the life of the car when it’s driven the way it needs to be. Short trips and maintenance problems shorten a DPF’s life.
Is It Legal To Remove A DPF?
No. It’s illegal to drive a car that should have a DPF without one, and it will fail the MOT.
Do Petrol Cars Have DPF Problems?
Some newer petrol cars have a similar gasoline particulate filter (GPF), but these clog far less often because petrol engines run hotter and produce less soot.
Does A Vehicle History Check Show DPF Problems?
A history check shows MOT emissions failures, mileage and write-off records. The mechanical condition of the filter needs a test drive or inspection, so use both.
Conclusion
DPF problems are less about the badge on the car and more about how it’s been driven and maintained. A diesel that’s done regular longer journeys, been serviced with the right oil and passes its MOT emissions test cleanly can still be an excellent, economical buy. Check the MOT history and service records, take a proper test drive, and run a full history check before you commit.

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Related Guides
Table of Contents
1.
How Does A DPF Work?
2.
Which Cars Are Most Likely To Have DPF Problems?
3.
Warning Signs Of A DPF Problem
4.
How Much Does A DPF Cost To Fix?
5.
DPFs And The MOT
6.
What To Check Before Buying A Used Diesel
7.
Take Our Used Car Checklist To The Viewing
8.
Should You Still Buy A Diesel?
9.
Which CarVerified Report Covers This?
10.
Frequently Asked Questions
11.
Conclusion
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