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

Air Fuel Ratio

Scan tool displays 0.0-25.5. Air Fuel Ratio indicates the PCM commanded value. In Closed Loop, the air-to-fuel ratio should normally be approximately 14.2-14.7. A lower air-to-fuel ratio indicates a richer commanded mixture, which may by seen during Power Enrichment or Three-Way Catalytic Converter (TWC) Protection modes. A higher air-to-fuel ratio indicates a leaner commanded mixture. This can be seen during Decel Fuel mode.