A system for identifying a modification of a component in an exhaust gas line of a motor vehicle, includes a particulate filter, a diagnostic system, a first temperature sensor, a second temperature sensor, and an evaluation unit. The evaluation unit is configured to receive from the first temperature sensor a first temperature variable which is characteristic of a first exhaust gas temperature and to receive from the second temperature sensor a second temperature variable which is characteristic of a second exhaust gas temperature. The evaluation unit is also configured to compare the temperature variables or comparison variables which are derived therefrom with each other. Depending on the comparison, the evaluation unit is also configured to determine a modification of the particulate filter.