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How does SCR system work?

Selective Catalytic Reduction (SCR) is an after treatment technology that uses AdBlue to reduce harmful NOx emissions. The main components of the SCR system are the AdBlue dosing control and injection unit, SCR catalyst and the AdBlue tank.

AdBlue is injected from the vehicle’s dedicated AdBlue storage tank into the exhaust pipe, which is in front of the SCR catalyst, but downstream of the engine. As it is heated in the exhaust, the AdBlue changes into ammonia (NH₃) and carbon dioxide (CO₂). When the nitrogen oxide (NOx) gases from the exhaust pipe react inside the catalyst with the ammonia, the harmful NOx molecules in the exhaust are converted into harmless nitrogen and water, which is released to the atmosphere as steam.

Using AdBlue of poor quality that does not conform to the ISO 22241 standards can lead to costly repairs of SCR system.