The invention relates to a method for adapting a required catalyst temperature range for a NOx storage catalyst (18) which is arranged in the exhaust gas flow of a combustion engine and which is supplied by a lean exhaust gas, wherein (a) a nominal NOx storage capacity is determined by means of a model during a lean operation, (b) an actual NOx storage capacity is monitored by means of a gas sensor (22) which lies upstream from the NOx storage catalyst (18), (c) regeneration of the NOx storage catalyst (18) is triggered when a limiting value is reached for the actual NOx storage capacity, (d) the adaptation is carried out during the lean operation or when regeneration is triggered (adaptation time), (e) the deviation of the actual NOx storage capacity in relation to the nominal NOx storage capacity is determined at the adaptation time, and (f) an upper (G1) and/or a lower limiting temperature (G2) for the required catalyst temperature range is changed according to the sign and the extent of the deviation.