Method and apparatus for judging the functioning of a catalytic converter

摘要

A method, including an amplitude evaluation of control oscillations of the oxygen content of the exhaust gas of an internal combustion engine in front of and behind a catalytic converter, for judging the operating condition of the converter in order to determine whether the performance of the catalytic converter has deteriorated past a predetermined point. As soon as this condition is detected using the amplitude evaluation, switching is effected to the frequency evaluation for judging the functioning of the catalytic converter.