O2 Volts

[Shannen Durphey]

Bruce Plecan wrote:
> 
> Per several off list letters I checked/doubled checked/thriple checked
> grounds and power for this bit of history.
>    I noted the following, using a 4 wire heated O2 sensor.  (General Motors)
> With no power to heater, 0.0v.   For approximately 30secs 0.0, and then
> quickly rose to .1v, then then slowly climbed higher.
> When hot, there was a nominal voltage of .28v at the O2 sensor lead wire.
> Exposing this sensor to 97% O2 (Medical Grade O2, as tested this am) it
> drifted to .030.-.032v.
> Exposing this sensor to the Butane from a cigarette lighter that was unlit
> immediately responded with a display of .7v......
> Your O2 sensor is a HC Sensor...
> Bruce and the staff at CSH, HQ
Ahh... Now I see.  Technically speaking, the O2 sensor should be
called an O2 differential sensor.  Or maybe a "lack of O2" sensor. ;
)  No, the sensor doesn't make a voltage when there is oxygen on the
sniffer side of the sensor.  It makes a voltage when there is no
oxygen on the sniffer side.  Now the Argon thing, I'd like to know
more about.  IIRC, the ecm supplies a bias voltage to the sensor to
prevent false readings like the ones you got in plain air.  
Shannen