An ACDelco GM Original Equipment NOx (Nitrogen Oxide) Sensor is a GM-recommended replacement for your vehicle's original component, and is an exhaust gas sensor that detects the nitrogen oxide content of the exhaust from diesel engines. This information is used by the engine management computer to adjust various parameters to reduce harmful emissions. This original equipment nitrogen oxide sensor has been manufactured to fit your GM vehicle, providing the same performance, durability, and service life you expect from General Motors.