I just read through my post and the original post and made some correction in my reply. Its very hard for me to keep the voltage, mixture, and direction of response clear and I had writen lean where rich was the right word.
I wrote all this to give a feeling of the necessary thought that has to be given to testing O2 sensors. Then I reread the original post and realized I had wasted my time. I can't possibly explain how this works to someone who doesn't even know that none of this takes place till the sensor is HOT, HOT, HOT.
Can I say this again HOOOOOOOOOOOOOOOT. Is that how you spell it?
BTW are you disconnecting the sensor and reading 0.05v on the wire to the sensor or are you reading it connected?
Bosch Master, ASE Master, L1
33 years MB technician