Patent ID: 8096171

Claim:
A method of diagnosing an internal combustion engine exhaust gas system that includes a particle filter, said method comprising: determining first and second set of value vectors, each vector comprising associated values for an absolute pressure upstream and downstream of the particle filter, a differential pressure determined from the absolute pressure values, an exhaust gas flow volume through the particle filter, and a temperature of the exhaust gas volume flow; determining temperature-standardised values for the absolute pressure upstream and downstream of the particle filter, and for the differential pressure, at least for the values of the first set of value vectors, such that temperature dependence for the values of the absolute pressure upstream and downstream of the particle filter and the differential pressure is substantially eliminated; based on the temperature-standardized values of the first set of value vectors, generating characteristics which represent dependence of the absolute pressure upstream and downstream of the particle filter, and of the differential pressure, on the volume flow; storing the characteristics as reference characteristics; comparing values for the absolute pressure upstream and downstream of the particle filter and the differential pressure of the second set of value vectors with pressure values derived from the reference characteristics; evaluating a comparison result with regard to a flow anomaly in the exhaust gas system.