02 sensor operation, chemical reaction or thermal reaction?

[resident_genius]

i've searched long and hard, maybe i've simply not hit the right place-

lets establish the basics-

when running rich, EGT drops, and there is less oxygen content in the exhaust, correct?

when running lean, EGT goes up, and there is more oxygen content in the exhaust, yes?

well then, is the generation of voltage directly related by a thermal reaction by the EGT, or is it a chemical reaction, and the oxygen molecules reacting with the catalyst in the sensor produces a voltage?

i have had many debates, however i cant seem to find a definitive answer.

people test 02 sensors by heating them with a torch, as we did in rudimentary shop class. i was told when the catalyst in the tip is heated, it gives off a voltage. others have argues otherwise.

[glenn_aircooled]

Firstly , I dont know the answer......
but I will make a wild guess and say that it is a Thermal reaction,
and then the engineers say " the exhaust gets hot when its running too lean - therefore too much Oxygen..."
-
The doubt I have to my guess is that they use some rare metal in the O2 sensors, and I thought that was there to cause a chemical reaction......
Lets hope someone knows..............
Glenn.

[hypersoniq]

[chemelec]

[resident_genius]

[readyakira]

Well, you could test the theory by heating it in a container full of air and read the voltages at a set temp, then fill the same container with a Gas, say helium then heat it again and compare the reading. This would tell you for sure I would think of the chemical reaction taking place. I am thinking it is more chemical then thermal, since even thermal there has to be a reaction causing the electrons to flow?

[biggeorge]

[chemelec]

[hydroxrox]