Preventive maintenance"this is the main reason being cited by the leading oxygen sensor manufacturers why they would advice BMW owners to replace the O2 sensors of their vehicles periodically. A damaged oxygen sensor can greatly increase the fuel consumption of a vehicle. Further, the failure of the BMW oxygen sensor may cause damages on other parts of the vehicle, especially on the catalytic converter which is necessary for emissions control.

An automotive oxygen sensor is a small electronic sensor inserted into the exhaust system of most engine-fueled vehicles, especially on those manufactured after 1980. Vehicles manufactured in the 1980s are usually equipped with one or two oxygen sensors, usually located on the branch manifold before the catalytic converter. This number, however, has been doubled after the introduction of the Onboard Diagnostic II (ODBII), with the added sensors usually placed after the catalytic converter to measure its efficiency.

The main function of automotive oxygen sensors is to measure the volume of oxygen remaining on the exhaust gas. The data obtained by the oxygen sensor would then be delivered to the engine management ECU computer. Based on this data, the ECU computer would then adjust the amount of fuel to be delivered to the engine. If the oxygen sensor gets damaged, this function of the ECU computer would be compromised, usually resulting to feeding the engine with more gasoline than what it actually needs. Such richness in the fuel-to-air ratio would also cause the catalytic converter to run hotter than normal, a condition that may lead to the eventual failure of the converter.

To prevent such things from happening, oxygen sensor manufacturers advise that oxygen sensors be replaced at regular intervals. For vehicles manufactured prior to the implementation of the OBDII, unheated oxygen sensors must be replaced after every 30,000 to 50,000 miles while heated oxygen sensors after every 60,000 miles. For those vehicles with OBDII (vehicles manufactured in the mid-1990s and newer), the replacement of oxygen sensors is recommended after every 100,000 miles.

By replacing the BMW oxygen sensor at the said intervals, BMW owners will be assured that the emission levels and the fuel consumption of their vehicles will be held at the minimum. The power generation of the vehicle's engine is also guaranteed to become more efficient.