An ACDelco GM Original Equipment Oxygen (O2) Sensor is a GM-recommended replacement for your vehicle's original component, and is a special feedback sensor on your vehicle's exhaust system. This sensor measures the proportion of oxygen in the exhaust gases. Using this measurement, the engine management computer can adjust the air/fuel ratio near the optimum value of 14.7:1. At this ratio, engine performance, emissions, and fuel economy are all optimized. This original equipment oxygen sensor has been manufactured to fit your GM vehicle, providing the same performance, durability, and service life you expect from General Motors.