Oxygen sensors — design description (Audi A4 B6)

To measure the oxygen content in the exhaust gas, one oxygen sensor is installed on the intake pipe of the catalytic converter, and the second one is installed after the converter. The sensors are designed to continuously measure the oxygen content in the exhaust gas. In accordance with the measured value, the control device gives a command to enrich or deplete the fuel-air mixture. This occurs in a rapidly changing sequence: excess air leads to the combustion of hydrocarbons, insufficient air leads to a decrease in the content of carbon oxides. The exhaust gases consisting of this mixture enter the catalytic converter, where the exhaust gases are almost completely converted into substances such as carbon dioxide, water vapor and nitrogen.