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NOx sensors

NOx sensors, i.e. nitrogen oxide sensors, are components installed in internal combustion vehicles and agricultural machinery. Their aim is to control the amount of nitrogen oxides released into the environment along with the exhaust fumes. They are part of the SCR (Selective Catalytic Reduction) system, the function of which is to reduce the emission of harmful substances contained in the exhaust gases into the atmosphere.
Arcoore offers NOx sensors for all brands of trucks and commercial vehicles.

NOx sensor – what is it for?

Nitrogen oxides (NOx) are one of the most dangerous components harmful to the atmosphere. In high concentrations, they can be very dangerous to health. They arise, among other things, in the combustion process in the engine and are then excreted through the exhaust system. Taking into account their enormous harmfulness to the environment, companies producing trucks try to design exhaust gas recirculation systems in such a way as to minimize the emission of harmful substances. The NOx sensor is part of the systems designed to reduce the emission of harmful substances.


The NOx sensor measures the concentration of the most important nitrogen oxides in the exhaust gas. These include nitrogen oxide (NO) and nitrogen dioxide NO2. Depending on the vehicle model and the design of the SCR system, they are placed either in front of the catalytic converter or behind it.
With NOx sensors you can:
 – pre-diagnose problems with the operation of the exhaust gas treatment system;
– find out when it needs maintenance;
– replace the correct components;
– add ad blue to the tank.
The target operation of the entire system is to clean the exhaust gases from excess harmful substances and ensure proper operation of the drive unit.


Defective NOx sensor – what can it cause?

A damaged nitrogen oxides sensor will cause that the composition of exhaust gases will not be optimal, and too much harmful substances will be emitted into the atmosphere. In addition, the correct operation of the engine may be disturbed, as well as increased fuel consumption.

Nitrogen oxides sensors are unfortunately exposed to mechanical and thermal damage mainly due to their location. The efficiency of the sensor should be checked with checking the condition of the wiring. It may happen that damaged cables are responsible for its malfunction. The sensor transmits information to the on-board diagnostics system.
Most often, the on-board computer signals the problem with the engine light. Often the car will automatically limit the engine power. Taking into account that the check engine light can also signal other faults, it is necessary to perform computer diagnostics. If the service determines that the errors indicate damage to the NOx sensor, it must be replaced. “


NOx sensor – how does it work?

The NOx sensor of nitrogen oxides is located directly in the exhaust system of the vehicle and is used to continuously measure the content of NOx (nitrogen oxides) in the exhaust gases of cars. It then sends the information to the engine control unit. Based on the received information, the controller controls the operation of the engine and other elements, e.g. Ad Blue dosing, so that the emitted exhaust gases contain as little harmful NOx components as possible.

Nitrogen oxides sensors have an active electrode which separates nitrogen and oxygen through catalysis. There are two chambers in the sensor. In the first one, the oxygen content is kept at about 10 ppm. However, it is in the second chamber that NOx catalysis takes place, as a result of which oxygen and nitrogen are separated. A current that is proportional to the NOx concentration is used to maintain the environment of the platinum-rhodium anaerobic electrode. It is this current that sends the measurement signal.


Why do we use nitrogen oxide sensors?

As a result of the need to modify vehicles in such a way that their operation was less and less harmful to the atmosphere, at the beginning of the 21st century, exhaust emission reduction systems began to be used in motor vehicles and utility vehicles. Currently produced vehicles must meet strict emission standards. The NOx sensor is environmentally friendly not only in reducing harmful substances in fuels, but also in reducing combustion and optimizing engine operation.

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