Operation CHARM: Car repair manuals for everyone.

TWC Protection

Scan Tool Displays ACTIVE or INACTIVE. ACTIVE displayed indicates that the PCM has detected conditions appropriate to operate in TWC Protection mode. This is determined based on Engine Load and Engine Coolant Temperature. While in TWC Protection, the PCM will decrease Air/Fuel Ratio to a value that depends on Mass Air Flow (higher Mass Airflow = lower Air/Fuel Ratio).