What is Nox Sensor?

February 5th, 2022

The nitrogen oxygen sensor is a sensor used to detect nitrogen oxide compounds in diesel engine exhaust. 

The nitrogen oxygen sensor will upload the detected nitrogen oxide concentration data to the on-board computer (i.e. ECU), which will control the urea injection amount of the SCR system based on the data, thereby reducing nitrogen oxide emissions and achieving OBD monitoring of SCR components.


In other words, without a nitrogen oxygen sensor, the ECU cannot accurately determine the concentration of nitrogen oxides in the exhaust gas, and thus cannot accurately control the urea injection amount of SCR. The nitrogen oxides in diesel vehicle exhaust cannot be effectively purified, and their concentration will exceed the national emission standards.

The nitrogen oxygen sensor is a mandatory accessory on heavy-duty diesel vehicles and must be replaced regularly. Under normal circumstances, the service life of the nitrogen oxygen sensor is 6000 hours.


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