What is the oxidation sensor on car?

Answer 1

The oxygen sensor, or O2 sensor, is located in the exhaust system. It is used to measure the amount of oxygen present in the combustion byproducts of the engine. This allows the computer to adjust the air-fuel mixture at the carburetor or fuel injector in order to optimize performance and emissions. Often, there are several sensors; one in each manifold header and, some times, one downstream of the catalytic converter.

It is important to realize that the O2 sensor is a very high impedance device, and that its reading can be biased and/or the device can be damaged, by attempting to measure its output voltage with the wrong kind of meter.