An ACDelco Professional, premium aftermarket Oxygen (O2) Sensor is the high quality replacement ideal for many vehicles on the road today. It is a special feedback sensor on your vehicles 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 premium aftermarket replacement oxygen sensor is manufactured to meet your expectations for fit, form, and function.