TWC Monitor Test Counter

The scan tool range is 0-49. The TWC monitor test counter increments while the TWC system diagnostic test is running and taking samples. When the TWC Monitor Test Counter reaches 49, the PCM will update the TWC diagnostic statistical filter. At this point, the TWC Monitor Test Counter will reset to 0 and begin incrementing again. The TWC Monitor Test Counter is most useful when verifying a 3-way catalytic converter replacement or any repair associated with the DTC P0420 diagnostic table.