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

The scan tool displays the PCM commanded air to fuel. Air fuel ratio should normally be around 14.2:1 - 14.7:1. A lower air fuel ratio indicates a richer air to fuel mixture. A higher air fuel ratio indicates a leaner commanded air to fuel mixture.