Catalytic Converter: Description and Operation

The three-way catalytic converter, together with the closed loop air-fuel ratio control based on the oxygen sensor signal, oxidizes carbon monoxides (CO) and hydrocarbons (HC) and reduces nitrogen oxides (NOx).

When the mixture is controlied at stoichiometric air-fuel ratio, the three-way catalytic converter provides the highest purIfication against the three constituents, namely, CO, HC and NOx.