yup- 650 mV! I lost a zero there! 65 mV would be very lean, indeed! -- Andy Quaas Andris Skulte wrote: > Umm... yes! :) Do you mean 650 mV? At 14.7 air:fuel, the o2 should read > around 500 mV, and when the computer is in closed loop, you should see > the o2s constantly jumping across 500 (maybe 200-700 range). > > Andris "the man of 1050 mV o2's" Skulte