What the light is telling you
The diesel particulate filter has collected more soot than it can hold and needs to burn it off. If the car cannot complete that process, soot turns to ash and the filter eventually needs forced regeneration, cleaning or replacement.
Why short journeys cause it
Passive regeneration needs sustained temperature — typically a steady run at speed. Town driving, school runs and delivery work never let the filter get hot enough.
What not to do
- Do not keep ignoring it — the repair cost rises as it blocks
- Do not keep clearing the code without fixing the cause
- Do not remove or gut the filter — it is an MOT failure and illegal for road use
- Do not assume additives will fix a mechanical or sensor fault
What we check
- Differential pressure and soot load readings
- Regeneration history and why attempts failed
- EGR operation and injector condition
- Oil level and dilution, which blocks regeneration