TWC Protection

Scan tool displays ACTIVE or INACTIVE. ACTIVE displayed indicates that the PCM has detected conditions appropriate to operate in Three-Way Catalytic Converter (TWC) Protection mode. This is determined based on the engine load and the engine coolant temperature. While in TWC Protection, the PCM will decrease the air-to-fuel to a value that depends on mass air flow. Higher mass air flow equals a lower air-to-fuel ratio.