Oxygen sensors are electronic devices installed in motor vehicles manufactured after 1980 to measure the ratio of oxygen in a car or truck's gasoline. When gasoline contains too little or too much oxygen, it is harmful to motor vehicles as well as the environment. In the case of too little oxygen, the fuel generates nitrogen-oxide pollutants, which negatively affect a car's performance and damage the engine, while too much oxygen creates air pollution.
In order to best detect the proportion of oxygen to gasoline in a vehicle, oxygen sensors are installed at strategic points throughout a car or truck's exhaust system. Sensors then generate voltage when they detect an oxygen-to-gasoline ratio that is too high or too low, which leads the engine computer to accordingly adjust how much fuel to expend. If an oxygen sensor is not working properly, the engine's computer is unable to calculate the correct fuel-to-air ratio, leading to mechanical problems or emissions violations.
Oxygen sensors also trigger dash lights notifying the car operator when there is a problem with the vehicle's oxygen-fuel mixture. This ensures the engine runs as efficiently as possible and that the car is not polluting the environment. The latter problem not only contributes to environmental degradation, it often results in car owners being fined by their state emissions regulation agency. Vehicle emissions inspectors are often able to detect past oxygen sensor notifications during their examinations of a car's emissions system.