The catalytic converter selectively converts nitrogen oxide (NOx) in the exhaust gases into nitrogen and water. To do this, it uses a synthetically produced aqueous urea solution, carried in an auxiliary tank. The substance, containing 32.5 per cent urea, is added continuously to the exhaust tract, upstream of the Selective Catalytic Reduction (SCR) catalytic converter. It is metered according to the mass flow rate of the exhaust gas and is precisely regulated by the engine management system, which receives information from the NOx sensor. NOx exhaust treatment is part of our BlueMotionTechnologies - our innovative energy saving and fuel efficient technologies.
Article source: www.volkswagen.co.uk