Operation CHARM: Car repair manuals for everyone.
Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the spiritual successor to CHARM, I recommend you try it!

Link: lemon-manuals.la or lemon-manuals.org.ua

(Some people have issue connecting. LEMON is investigating. For now, use Firefox or change your DNS server)

Or, hide this message: temporarily or permanently

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.