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,

 

12.8 volts should be enough for a heater. It's the same (or a little less) as the battery voltage. You can't get it higher.

Signal should be switching from lean (< 0.4 volt) to rich ( > 0.6 volt). That is the way closed loop is designed.

Was the co set at a correct level before? And if so, what was this? Something else may be wrong - like coolant temperature sensor or map sensor (hose).

 

Was in email with Stu - seems like most of these voltage issues are caused by the ageing wire/loom. I must go and rewire the fuel pump and probably the fans too.