Diagnosing functioning states of catalytic converter

摘要

The diagnostic system includes a detector (52,54) for determining the engine operating condition. A detector determines the amount of exhaust gas flowing through the catalytic converter. A diagnostic system differentiates between the normal state and a deterioration in a predetermined standard quantity zone where the quantity value assumes a specific value and a diagnosis of the normal state of the catalytic converter is carried out within a predetermined zone of larger amount lying above and outside the predetermined standard quantity zone. The diagnostic system interrupts the diagnosis of the normal state and of the deteriorated state of the catalyst within a predetermined zone with a particularly large amount of exhaust gas which lies above and outside the predetermined zone of large amount. The threshold is fixed despite a changing amount of exhaust gas.