The invention relates to a method for the quality assurance of exhaust gas behaviour in a motor vehicle (100), particularly in a hybrid vehicle, comprising: monitoring (10) an on-board-diagnosis (OBD) function (110); providing (20) a journey counter (120), a diagnosis counter (130), and a nominal diagnosis frequency value (140); incrementing (50) the journey counter (120) following the beginning of a driving cycle; generating (60) an actual diagnosis frequency value (160) using a combination of the diagnosis counter (130) and the drive counter (120); and establishing (70) a difference between the nominal diagnosis frequency value (140) and the actual diagnosis frequency value (160). If the difference falls short of a threshold: a control method (170) is selected (75), which is designed to successfully complete a currently running OBD of the OBD function (110) and to initiate and complete a non-running OBD. Following the completion of the OBD of the OBD function (110), the diagnosis counter (130) is incremented (80) and the motor control restored (90) to an original motor control. The invention further relates to a corresponding device (200) and to a corresponding motor vehicle (100).