Are diesel particulate filters more trouble than they’re worth?

Published: 26 August 2011

If you’ve seen the latest September 2011 issue of CAR Magazine, you might have noticed a news story about diesel particulate filters, and how a failing one could land you with a £1500 repair bill that isn’t covered by any warranty.

DPFs started appearing on diesel cars a decade ago. Like  catalytic converters on petrol cars, they sit in the exhaust pipe and trap harmful particulates before they have a chance to escape to the atmosphere.

Diesel particulate filters: when they go wrong

The problem is that prolonged town use can choke them up. If that happens a warning light will appear on the dash recommending you start a regeneration process to burn it off. This can involve driving for 20 minutes at a constant 40mph – easier said than done if you live in the middle of London. If you ignore the light a second may then appear, by which time your DPF has had it and a big bill is heading your way.

One way of slashing that bill however, is to have the DPF removed. You don’t need a DPF to pass an MOT and numerous companies like Cheshire-based DPF Removal ( can whip that section of the exhaust off, hollow out the filter part and put it back together, giving a stock appearance.

The car’s ECU will then need to be remapped to suit though, or it won’t run correctly. DPF Removal will do the lot for £400-500. Business is brisk, according to owner Jason Copeland, suggesting that people don’t really care how many noxious substances they project into the air, as long as they can save a few quid.

Are DPFs suitable for all motorists?

Manufacturers claim that salesman are trained to explain to would-be buyers that diesel cars fitted with DPFs might not be suitable for someone doing mostly urban mileage. But the trouble is that many cars fitted with DPFs are now five years old and on their second or third owners, who will likely have no idea of a DPF’s quirks.

Although we’ve always had at least a couple of diesel cars on our long term fleet at a time, we’ve never seen a DPF warning flash up on the dashboard. But as CAR’s office is located in England’s Midlands, our cars get plenty of opportunity to stretch their legs.

Have any of you been hit by DPF repair bills? Are you out every Wednesday crawling along like a pensioner to try and regenerate the thing and clear it out? Or have you junked yours altogether?

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By Chris Chilton

Contributing editor, ace driver, wit supplier, mischief maker