Method of operating an aftertreatment device in an automotive system

An internal combustion engine exhaust gas aftertreatment device 280 in an automotive system, and a method of operation. The aftertreatment device comprises a catalytic converter 287. The method comprises the step of, and the device comprises means for, warming-up a selected portion 292 of the catalytic converter earlier than the rest of the catalytic converter to a temperature higher than or equal to an activation temperature value for activating an exothermic reaction in the exhaust gas flow, i.e. the light-off temperature. The selected portion may have a greater average concentration of a catalyst substance than the rest of the catalytic converter. The overall exhaust gas flow may be directed onto the selected portion, and the speed of the exhaust gas may be increased. Each of these may be effected by actuation of a shutter (293, figures 4-9) upstream of the selected portion. The selected portion may comprise a heating element, such as an electrical resistance element.