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The stricter emissions legislation in the US, require the implementation of Diesel Particulate Filters (DPF) for Heavy Duty Diesel engines to meet the 2007 PM emissions targets. Cordierite based wall-flow filters with high filtration efficiency, low Δp and good thermal durability are the product of choice for these applications. Continuous passive oxidation of the soot by NO2 is desired, however under certain operating and ambient conditions periodic active oxidation of the soot at elevated temperatures (>550°C) is required. A part of the PM emissions of the engine contains non-combustible contributions (ashes). These materials accumulate in the filter over lifetime, resulting in an increase in pressure drop as well as a reduction of the filter volume available for soot accumulation. As the pressure drop rises above manageable levels from a performance perspective, ash cleaning of the filter is required.