DTC P0140: Ho2S Circuit Insufficient Activity - Bank 1, Sensor 2: Description

To control emissions of Hydrocarbons (HC), Carbon Monoxide (CO), and Oxides of Nitrogen (NOx), a 3-way catalytic converter is used. The catalyst within the converter promotes a chemical reaction which oxidizes HC and CO present in exhaust gas, converting these chemicals into harmless water vapor and carbon dioxide. The catalyst also reduces NOx, converting NOx to nitrogen. PCM has the ability to monitor this process using post-catalyst Heated Oxygen Sensor (HO2S). This sensor produces an output signal which indicates oxygen storage capacity of the catalyst. This in turn indicates the catalyst's ability to convert exhaust gases efficiently. If post HO2S signal voltage remains at or near 450 mV bias for an extended period of time, this DTC will set.