Peugeot SCR (Selective Catalytic Reduction) system is an advanced exhaust control system technology which have been launched, mainly used on diesel engines to reduce nitrogen oxides (NOx) emissions. This system injects a urea-based liquid--known as Diesel Exhaust Fluid (DEF)--into the exhaust stream. Mixed with DEF, the NOx in the presence of a catalyst will be converted into harmless nitrogen and steam. Functions of the Peugeot SCR system include engine optimization, meeting the strictest of emission standards and performance improvement. Technological characteristics include real-time monitoring of the exhaust gas, accurate DEF dosing and an advanced catalytic converter. Its applications can be found in a wide range of models of Peugeot cars, but especially those with bigger diesel engines. This is to bring about a cleaner and more sustainable driving experience.