Simply Auto DPFC1 DPF Cleaner 500ml Active Foam SprayA DPF warning light is an expensive thing to ignore and an expensive thing to fix. Replacement filters run to several hundred pounds, and a professional off-car clean is not far behind. Before either, it is worth trying to clear the filter where it sits.Simply Auto DPF Cleaner is designed to be applied on the car. The temperature or pressure sensor is removed, the applicator goes into the port, and the contents are emptied directly into the filter. No exhaust work, no dismantling, no lifting the car onto a ramp.The formula foams on contact. That is the point of an active foam rather than a liquid: foam expands to fill the honeycomb channels inside the filter and stays in contact with the deposits, where a thin liquid would simply drain through to the lowest point. It dissolves the soot and carbon that build up over short journeys and stop-start driving, which is where most DPF problems begin.It is non-corrosive, so it will not attack the filter substrate or the surrounding pipework, and it works within minutes rather than requiring a long motorway run afterwards.A restricted filter costs you more than a warning light. Exhaust gas has to push through the blockage, and that backpressure shows up as heavier fuel consumption and duller throttle response. Clearing the deposits helps recover both.Suitable for most diesel cars and light commercial vehicles fitted with a particulate filter. One 500ml can treats a single filter.Note: This spray treats soot and carbon loading, which covers most filters that clog through urban driving. A filter that has been left too long, or that is loaded with incombustible ash after very high mileage, may be beyond “in place” cleaning and need professional treatment or replacement. If the light returns quickly after treatment, that is usually the reason.