Air/fuel Ratio

Scan tool range 0.0 to 25.5. Air Fuel Ratio indicates the PCM commanded value. In closed loop, 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.