Catalyst Monitor Heated Oxygen Sensors

Catalyst Monitor Heated Oxygen Sensors
To control emissions of Hydrocarbons (HC), Carbon Monoxide (CO), and Oxides of Nitrogen (NOx), a three-way catalytic converter is used. The catalyst within the converter promotes a chemical reaction which oxidizes the HC and CO present in the exhaust gas, converting them into harmless water vapor and carbon dioxide. The catalyst also reduces NOx, converting it to nitrogen. The Control Module has the ability to monitor this process using a HO2S 1 heated oxygen sensors. The HO2S 2 sensor produces an output signal which indicates the amount of oxygen present in the exhaust gas entering the three-way catalytic converter. The HO2S 2 sensor produces an output signal which indicates the oxygen storage capacity of the catalyst; this in turn indicates the catalyst's ability to convert exhaust gases efficiently. If the catalyst is operating efficiently, the HO2S 1 signal will be far more active than that produced by the HO2S 2 sensor.
In addition to catalyst monitoring, the HO2S 1 oxygen sensor has a limited role in controlling fuel delivery. If the HO2S 1 signal indicates a high or low oxygen content for an extended period of time while in closed loop, the Control Module will adjust fuel delivery slightly to compensate.