Jim,
There are two basic types of O2 sensors.
One produces a voltage (zirconium element) it is a battery that
functions by comparing the levels of oxygen in the exhaust and in the
atmosphere. The larger the difference the higher the voltage (rich
mixture produces around 1.0 volt on the high side.) An oxygen rich
exhaust (lean) produces a lower voltage (a low of about 0.1 volts.)
(The zirconium sensor is a one wire sensor. Some of the zirconium
sensors have three wires, the extra two wires are for a heating element
that brings the sensor to a functioning temperature quicker and keeps
the system in closed loop at idle.)
The second type does not produce a voltage, but acts like a variable
resistor altering the base voltage supplied by the computer. Rich
mixture gives a low resistance allowing a higher voltage to flow back to
the computer and when the mixture is lean, resistance increases,
lowering the voltage flow back to the computer.
Tom, Redding CA - #216 D/CC
Waldron, James wrote:
> I'm kind of a 'roll my own' kind of guy. Does anyone know exactly how O2
> sensors work. I know they have a special coating. Do they require power?
> Is it just a change in Resistance depending on how much O2 at a particular
> temperature?
>
> Thanks,
> Jim.
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