Circuit Description

Three-Way Catalyst (TWC) system is used to control emissions. PCM uses signal from Heated Oxygen Sensor 2 (HO2S 2) behind TWC to read efficiency of TWC. PCM will set this DTC if TWC oxygen storage capacity is less than a predetermined threshold.

For duplication of DTC, ensure no active misfire, fuel injector circuit, fuel trim, EGR, EVAP system, TP, IAT, MAP, ECT, MAF or CKP sensor DTCs are set, engine is running, and engine coolant temperature is greater than 149°F (65°C).