Abstract: During a first driving cycle, a combustion process is controlled in at least one combustion chamber for the purpose of performing a check on an emission reduction system of an internal combustion engine. During a second driving cycle following the first cycle, a check is performed to establish whether an error in the emission reduction system was detected during the first cycle. An idle time between the first and the second cycles is determined, in the event of an error of the emission reduction system detected during the first cycle. During the second cycle, the combustion process in the at least one combustion chamber is only controlled for the purpose of the check on the emission reduction system, in the event of an error detected in the emission reduction system during the first cycle and in the event of the idle time being longer than a pre-determined repair time.