Catalytic Converter Monitoring

The new catalytic converter monitoring function enables the DME to monitor the efficiency of the catalytic converter. This function is made possible by the additional input signal of the second O2 sensor.

When operating effectively, the catalytic converter consumes most of the oxygen in the exhaust gas. The sampled post catalytic converter exhaust gas is therefore very low in oxygen which the O2 sensor signals as a relatively steady 0.8 volt signal.

The DME compares the pre and post cat input signals separately to a pre-programmed set limit. If the oxygen content rises above the set limit for that range of engine operation, the DME recognizes this as an inability of the catalytic converter to effectively consume oxygen. This is a direct indication of catalytic converter failing condition due to age or contamination.