I’ve seen a number of products on the market now for what are termed DPF maintenance, or somewhat similar words, the upshot being that regular DIY use of them will prevent DPF clogging, or for one-off use will solve a clogged DPF. One of them was featured in Issue 326 of Gadget Inspector. Does this mean an end to DPF problems and worries for diesel owners, and what other reports do you have to date on the products in question?
Rob Barnes, Ipswich

There are indeed a number of such products around, although I’m afraid that we at Diesel Car have somewhat limited knowledge regarding their effectiveness, as cars that we run as long-termers get regular long runs on open roads and don’t suffer from DPF problems. The active component of these products, which are added to the fuel tank, usually on a one-shot basis, or maybe every few tankfuls of fuel, depending on the severity of the problems, is usually a catalyst that reduces the DPF regeneration temperature. It therefore helps the engine keep the DPF cleaner during normal operation, as well as hopefully cleaning up a DPF that is giving problems due to lack of long runs. Most of the products seem to come from respectable companies and the Millers Diesel Particulate Filter and Regenerator that we featured in Issue 326 was tested with effective results on a 1.6 HDi engine that was slipping into regeneration mode rather too often, although it had displayed no emissions warning lights that indicate more serious problems. Other DPF maintenance services, mostly to solve serious DPF blockage problems, use detergents and/or high temperature treatment to clean out existing accumulations of particulates, and most of these involve removal of the DPF for cleaning and replacement, and are performed by trained operators at garages or are sent away to specialist companies. So we would be very interested to hear of any reader experiences. Many thanks for your letter Rob.
Doc Diesel