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 ratio to a value that depends on Mass Air Flow (MAF). Higher MAF equals a lower air-to-fuel ratio.