Method for the diagnosis of a three-way-catalytic converter for an internal combustion engine

Abstract

A method for the diagnosis of a three-way catalytic converter for an internal combustion engine using the voltage signal of a downstream binary lambda sensor proposes that with a changeover of the air/fuel ratio λ that is fed to the internal combustion engine from high to low, the voltage signal Uλ of the lambda sensor is monitored for its jump in order to establish a first oxygen storage capacity OSC1 of the catalytic converter, with a changeover of the air/fuel ratio that is fed to the internal combustion engine from low to high, the voltage signal Uλ of the lambda sensor is monitored for its jump in order to establish a second oxygen storage capacity OSC2 of the catalytic converter, and/or with a modulation of the air/fuel ratio that is fed to the internal combustion engine between high and low, the voltage signal Uλ of the lambda sensor is monitored for its jumps in order to establish a third oxygen storage capacity OSC3 of the catalytic converter, wherein the diagnosis of the catalytic converter is performed based on the ratio between two of the three oxygen storage capacities. According to the proposal, a diagnostic method differentiated with regard to reversible and irreversible damage, as well as with regard to oxidizing and reducing capabilities is provided.

Dependencies are inferred from the claim text.