Did some checking on the lambda sensor last weekend due to fuel economy going south.

Start test at idle and warmed up - I have 12.8 volts going to the lambda sensor. The signal is .82 volts and I seem to have .08 volts on the earth wire. CO was running at 6% at idle (way too rich)

Re-set the ecu screw as per instructions for closed loop. – signal falls to .03 and 0 and then rises to .68 and jumps around to .44 to .7 . and sometimes back to 0 again. CO drops and goes up and down between .5% and 1.0% Does this mean the sensor is still working?

Is 12.8Vs high enough to heat the sensor - What should I look at to get this voltage higher if required?

Thanks,