OK,

after testing my old O2 sensor and finding it faulty I got another one ... universal 3 wire, solder yourself type...

got the new one in (old one removed ... looks like metal cover busted off and must now be residing in my exhaust downstream of the sensor hole!)

thought I'd test the new sensor while I had access to a good Digital Multimeter..

here's the results:

after driving for 15 min. to warm up sensor I disconnected the main signal wire from ECU - hooked up meter... started car,

while revving I
checked voltage at the signal wire that goes to the sensor: .02V to .03V fluctuating between those two very low voltages

stopped revving and
checked voltage at the signal wire that comes from the ECU: .52 V solid

last night I checked the voltages while the wires were connected and the signal was even lower fluctuating between -.004V and + .004 V

I know the two heater wires have 12 V and grnd respectively

FWIW the resistance across the heater wires of the sensor when cold is appx. 5 Ohms, same resistance when hot is 11.5 Ohms - these values are slightly out of spec according to Bentley.

Art Benstein suggested I might have a short in a wire somewhere...

is there anything I could be doing wrong before I send back what looks to be a NEW faulty sensor?

--
Bad Blue, '86 245, 244,000 mi.