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)

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AIR Fuel Ratio

The scan tool range is 0.0 to 25.5. The air fuel ratio indicates the PCM commanded value. In a closed loop, the air fuel ratio should normally be around 14.2-14.7. A lower air fuel ratio indicates a richer commanded mixture, which may be seen during Power Enrichment or Three-way Catalytic Converter (TWC) Protection modes. A higher air fuel ratio indicates a leaner commanded mixture. This can be seen during Decel Fuel Mode.