Diesel particulate filter (DPF) problems explained
Why DPFs block and how to avoid an expensive replacement.
Published 15/10/2026
Diesel cars built since 2009 have a DPF that traps soot. It cleans itself by burning the soot off, called regeneration, which needs a sustained run at speed.
Why they block
Lots of short, slow journeys stop regeneration from finishing.
Signs
- A DPF warning light
- Loss of power or limp mode
- More frequent cooling fan running after you park
What to do
A 20 minute run on a dual carriageway can help. If the light stays on, a garage can run a forced regeneration or clean the filter, which costs far less than replacing it.
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