What does the DPF warning light mean?

The diesel particulate filter is full of soot and needs to regenerate. If you ignore it, the filter blocks and the car goes into limp mode.

Here's a quick, honest answer from a working UK mechanic — what causes it, what it costs to fix, and what to do next.

Can I remove the DPF? — No — DPF removal is illegal on UK roads since 2014 and is an automatic MOT failure.

Is the DPF light an MOT failure? — Yes if illuminated when presented for test, on cars first used after February 2014.