Patent ID: 7131261
Filing Date: 2006-11-07
Classification: F01N,F02D,Y02T

Abstract:
1. A method for diagnosing a catalytic converter, which is arranged in an exhaust-gas system of an internal combustion engine, the method having the steps of: detecting a signal (USHK) of an exhaust-gas probe downstream of said catalytic converter with said signal (USHK) having an amplitude (AHK); forming a limit value model amplitude (AHKF) from at least one quantity (ML, n) which occurs upstream of said catalytic converter; forming a catalytic converter evaluation quantity (DKATI) whose value increases with increasing deviation of said amplitude (AHK) of said signal (USHK) from said limit value model amplitude (AHKF); evaluating the operability of said catalytic converter on the basis of said catalytic converter evaluation quantity (DKATI); and, stopping the evaluation when an oxygen-dependent catalytic converter load (KATIN) exceeds or drops below a threshold value dependent upon said signal (USHK) of said exhaust-gas probe downstream of said catalytic converter.