Verify your meter by measuring battery voltage.

It seems that you said you had closed loop duty cycle readings in one of your posts. That is all that matters about an oxygen sensor. The switch time gives a good idea about age and sensitivity and the duty cycle tells you the mixture.

If you want a specified low voltage standard to go on. Unplug the sensor and read the wire coming from the control unit, it should be .45v

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician