Method and device for controlling an exhaust gas aftertreatment system

The method involves determining a state parameter characterizing the state of the exhaust gas treatment system starting from a first measurement parameter (DP), determining a correction parameter taking into account the dependence of the first measurement parameter on a second parameter and using it to correct the state parameter. Independent claims are also included for the following: an arrangement for controling exhaust gas treatment system, a computer program for implementing the inventive method and a computer program product for implementing the inventive method.