The process of burning off accumulated soot in a diesel particulate filter is called regeneration. A diesel particulate filter, or DPF, traps soot particles in the exhaust so they do not leave the engine as fine particulate pollution.
As soot accumulates, it increases exhaust back pressure. During regeneration, the trapped carbon is oxidized at a high temperature and converted mainly into gases, reducing the soot load and restoring the filter’s flow capacity. Passive regeneration can occur when normal driving produces sufficiently hot exhaust, while active regeneration deliberately raises exhaust temperature through engine-control strategies, additional fuel, or other heating methods.
Regeneration is not the same as ordinary cleaning. Cleaning is a maintenance operation, often performed off the vehicle, that removes ash and deposits that remain after soot has burned. Nor is “combustion” the usual name for the complete process: combustion or oxidation describes the chemistry, while regeneration names the filter-maintenance cycle. Drivers may notice higher idle speed, increased exhaust heat, or temporarily different fuel consumption during an active regeneration cycle.