Method and device for determining the amount of particles present in a filter means in the exhaust system of an combustion engine

The procedure consists of first establishing a relationship between the permeability of the exhaust filter medium (10) and the load of particles contained in it and storing this relationship in an accessible memory while the particle load is determined. Values are then determined for a series of parameters i.e. the difference in pressures between the inlet and outlet (14, 16) of the filter medium and for the flow of gas through the filter medium. These values are used to calculate a value for the permeability of the filter medium, and this value is used in the stored relationship to determine the particle load in the filter medium.