Mode II (Mixture Ratio Feedback Monitor)

In Mode II, both Red LED and Green LED are used to monitor air/fuel mixture feedback control. Green LED will function as in Mode I. In open loop, Red LED and Green LED will remain on or off. For results to be valid, vehicle must be in closed loop. In closed loop, Red LED will indicate if system is running rich (light off), lean (light on) or at ideal air/fuel ratio (blinking synchronized with Green LED).