The main function of a NOx sensor is to provide real-time feedback to the engine control unit (ECU) about the concentration of NOx gases in the exhaust stream. This information is crucial for the engine management system to adjust the air-fuel ratio and optimize the combustion process accordingly.

Working Principle of NOx Sensor:

• Detection of NOx Gases: The NOx sensor detects the concentration of nitrogen oxides (NOx), which typically include nitrogen monoxide (NO) and nitrogen dioxide (NO2), in the exhaust gases.
• Sensing Element: The sensor contains a ceramic element coated with electrodes and a catalyst material. When exposed to the exhaust gases, NOx molecules interact with the sensing element.
• Electrochemical Reaction: When NOx gases come into contact with the sensing element, an electrochemical reaction occurs. This reaction generates a measurable electric signal, usually in the form of a voltage.
• Signal Output: The electric signal generated by the sensor is sent to the engine control unit (ECU). The ECU interprets this signal to determine the concentration of NOx in the exhaust gases.
• Feedback Control: Based on the NOx concentration data received from the sensor, the ECU adjusts the engine parameters such as fuel injection timing, exhaust gas recirculation (EGR) rate, and selective catalytic reduction (SCR) system operation. This adjustment helps in optimizing the combustion process to reduce NOx emissions.

• Limp mode problem
• Malfunction light coming on (Check Engine Light)
• Increase in Exhaust Emissions
• Increase in Fuel Consumption
• Abnormal Exhaust Gas Color and Smell
• Heating Problems