The Audi oxygen sensor is one of the many new types of auto parts that are designed to help improve the performance of your car's engine and its mileage while reducing the amount of harmful emissions that escape into the atmosphere from the engine's exhaust. This engine sensor on your Audi is placed on the exhaust manifold in most instances. It can also be placed on the exhaust pipe just blow the manifold. The function of the oxygen sensor is to analyze the difference between the atmospheric oxygen to what your engine is producing after the combustion of the fuel. The reason the oxygen sensor on your Audi does not read the actual amount of oxygen but rather does a comparison is because oxygen levels in the atmosphere vary depending on the elevation and moisture content of the surrounding air. The comparison makes it possible for the computer in your car to make the correct adjustments to the fuel and air mixture so top performance of your engine can be achieved no matter where you are driving. Because technology is constantly improving, the new Audi oxygen sensors on the latest models are different than the ones used in previous years. This can be seen by observing the types of oxygen sensors and the same model Audi with just the difference being the year it was manufactured. The oxygen sensor used in your car is made to match up specifically with the engine and computer software used for that year. The use of a new style of this engine sensor is not recommended and highly discouraged. It will affect the performance of the engine and cause your mileage to be decreased along with shortening the life span of your automobile.