GM Genuine Parts oxygen (O2) sensors are special feedback sensors on your vehicle's exhaust system and are GM-recommended replacements for your vehicle's original components. They measure the proportion of oxygen in exhaust gases, then using the measurement, the engine control module (ECM) can adjust the air/fuel ratio to near the optimal value of 14.7:1. At this ratio, engine performance, emissions, and fuel economy are all optimized. GM Genuine Parts are the true OE parts installed during the production of or validated by General Motors for GM vehicles. Choose the O2 sensor designed for your vehicle.