Patent ID: 6216448
Filing Date: 2001-04-17
Classification: F01N,Y02T

Abstract:
A method of diagnosing a catalytic converter arranged in the exhaust-gas system of an internal combustion engine, the catalytic converter being configured to have an oxygen storage capability and a nitrogen oxide storage capability, the method comprising the steps of:providing and mounting a signal-emitting exhaust-gas probe rearward of said catalytic converter;repeatedly increasing and decreasing the oxygen concentration of the exhaust gas forward of said catalytic converter in such a manner that the signal of said exhaust-gas probe changes to reflect the increase and decrease of said oxygen concentration;detecting a first phase shift between a decrease of said oxygen concentration and a subsequent reaction of said exhaust-gas probe and detecting a second phase shift between a subsequent increase in said oxygen concentration and a subsequent reaction of said exhaust-gas probe;determining the difference between said first and second phase shifts; and,outputting and/or storing a fault signal when said difference does not reach a pregiven threshold.