Selective Catalytic Reduction (SCR) Deactivation

In order to comply with increasingly strict emission standards worldwide, engine manufacturers must reduce not only particulate matter emissions but also nitrogen oxide emissions. To meet this challenge, the selective catalytic reduction (SCR) system was invented. In the case of selective catalytic reduction, a catalytic converter converts the nitrogen oxides in the exhaust gas into water vapor and nitrogen. To achieve this, a metering module continually injects a reducing agent into the exhaust gas flow. The fluid reacts within a fraction of a second in the exhaust gas flow to produce ammonia, which then converts the nitrogen oxides in the SCR catalytic converter. However, there may be situations where it is necessary to disable the SCR system in the engine control unit, for example, to determine the exact cause of a vehicle malfunction and eliminate other options.