Air/Fuel Ratio

The scan tool displays 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 TWC Protection modes. A higher air fuel ratio indicates a leaner commanded mixture. This can be seen during Decel Fuel Mode.