The nitrogen and oxygen sensor (NOx sensor) is used to measure the nitrogen and oxygen concentrations in engine exhaust to meet the requirements of closed-loop control of the engine after-treatment system and the on-board OBD diagnostic system. It is generally installed at the rear end of the catalyst in the exhaust pipe. It CAN be applied to gas engines or diesel engines. Its structure includes a ceramic probe, cables and a processing chip controller, which is connected to the ECU through CAN communication.

氮氧传感器(NOx sensor)用于测量发动机尾气中氮氧浓度，以满足发动机后处理系统闭环控制的需要及车载OBD诊断系统的需要。一般装在排气管的催化剂后端。可应用于气体机或者柴油发动机，其结构包括陶瓷探头、线缆和处理芯片控制器，通过CAN通讯和ECU进行通讯连接。
NOX传感器的主要作用是检测排气中的NOX浓度值是否超限，同时为诊断催化器是否老化、拆除等故障作为依据。