Catalyst Monitoring

A 3-Way Catalytic Converter (TWC) 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 arid 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 Engine Control Module (ECM) monitors this process by using the bank 1 Heated Oxygen Sensor (HO2S) 2 and the bank 2 HO2S 2. The front HO2S produce an output signal that indicates how much oxygen is present in the exhaust gas entering the TWC. The rear HO2S produce an output signal that indicates the oxygen storage capacity of the catalyst. The catalysts oxygen storage capacity indicates the catalysts ability to convert the exhaust gases efficiently.