use of a crystal in auto sensor

[Guest guest]

A friend of mine sent me this little snippet of information. I am checking

with him for a link to the site he got it from:

 

To understand how the oxygen sensor knows the difference between rich and

lean, think of it like you would a battery. Oxygen sensors contain a crystal

that is sensitive to oxygen. These crystals produce a small voltage when

there

is more oxygen on one side of the crystal than the other. When the mixture is

 

lean, there is a small difference in oxygen content between the exhaust and

the atmosphere, so the crystal produces a low voltage. The exhaust from a

rich mixture has less oxygen than is in the air, so the crystal produces a

higher

voltage. Normal voltage ranges from one hundred millivolts (lean) to nine

hundred millivolts (rich).