Post-Catalyst (Rear)

A three-way catalytic converter is used to control emissions of Hydrocarbons (HC), Carbon Monoxide (CO), and Oxides Of Nitrogen (NOx). The catalyst within the converter promotes a chemical reaction that oxidizes the HC and the CO present in the exhaust gas, converting the HC and the CO into harmless water vapor and carbon dioxide. The catalyst also reduces NOx, converting the NOx to nitrogen. The ECM monitors this process by using the Bank 1 HO2S 2 and the Bank 2 HO2S 2 heated oxygen sensors. The front HO2S sensors produce an output signal that indicates how much oxygen is present in the exhaust gas entering the three-way catalytic converter. The rear HO2S sensors produce an output signal that indicates the oxygen storage capacity of the catalyst. The catalyst's oxygen storage capacity indicates the catalyst's ability to convert the exhaust gases efficiently.