Air/fuel Ratio

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.