Selective Catalytic Reduction (SCR) System - Transit

The SCR system reduces nitrogen oxides (NOx) in the exhaust stream by a chemical reduction process using the SCR catalyst and a reductant injection system that introduces diesel exhaust fluid (DEF) into the exhaust system upstream of the SCR catalyst. The reductant injection system is directly controlled and monitored by the reductant dosage control module. For additional information on the SCR system components, refer to ENGINE CONTROL COMPONENTS .