Click here for more information. When the combustion process is improved by proper vaporization of the fuel, then the exhaust oxygen content will rise. This might sound contradictory and you may expect that the more complete combustion would use up more oxygen. The opposite is what happens in reality. Less nitrogen oxides are produced and this means more free oxygen.
Gasoline is predominately carbon and hydrogen.
The exhaust products are a mixture of carbon monoxide, carbon dioxide, water, unburned hydrocarbon molecules, oxygen, nitrogen and oxides of nitrogen. As well as all the other nasty additives that are included in fuel these days. The catalytic converter is used to complete the process and thus reduce pollution. Additional air is added prior to the converter to enable it to function. How does the oxygen sensor work Nearly all automotive sensors are of the zirconia type.