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.