Keeping your diesel particulate filter (DPF) clean will save you thousands in the long run. Did you know just under 1kg of unburnt ash can be stuck inside a dirty DPF? When your filter is full, it can cause a series of major problems for your vehicles, including: increased downtime for regeneration (the burning of ash in your DPF), reduced fuel economy, loss of horsepower, serious damage to your DPF and eventually damage to your engine.