The NOx sensor is a sensor that measures the nitrogen oxide (NOx) levels contained in the exhaust gases of automobiles and other motor vehicles. This sensor detects the level of harmful gases released by the vehicle's exhaust system, helping to increase the efficiency of emission control systems and ensure less harmful emissions into the environment. NOx sensors help provide a cleaner and greener driving experience by increasing engine efficiency. These sensors are usually located near the exhaust pipe or exhaust manifold and provide information to the control unit in the vehicle.