Air/fuel Ratio

Scan Tool Displays 0.0-25.5 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.