Diagnostic method and diagnostic system for a particle filter of an internal combustion engine, in particular for a soot filter in a diesel motor vehicle

A diagnostic method is provided for a particle filter arranged in exhaust-gas flow of an internal combustion engine. A particle concentration is detected by a particle sensor positioned downstream of the particle filter. The combustion-relevant engine parameters are briefly changed by an engine controller in such a way that an untreated emissions concentration from the engine is significantly increased. A filter fault message is output if the detected associated measurement values of the particle concentration exceed a detection threshold value of the particle sensor, which is in particular considerably greater than a predefined, preferably volume-related particle limit value.