Air/fuel Ratio

The scan tool range is 0.0 to 25.5. The air/fuel ratio indicates the PCM commanded value. In closed loop, the 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.