Circuit Description

A Three-Way Catalytic (TWC) converter is used to maintain low emissions. The PCM monitors exhaust gasses from converter using Bank 2 HO2S 2, located in exhaust stream past the TWC converter. These sensors produce an output signal which indicates the oxygen capacity of the catalyst. This determines the catalysts ability to convert exhaust emissions effectively.

During normal operation Bank 2 HO2S 2 signal will be far less active than that produced by the Bank 2 HO2S 1. If a problem exists causing the PCM to detect excessive Bank 2 HO2S 2 activity outside of an acceptable range for an extended period of time, PCM will set a DTC. This indicates that the 3-way catalytic converter's oxygen storage capacity is less than the acceptable range.