This class covers the EGR (Exhaust Gas Recirculation), Diesel Oxidation Catalyst (DOC), Diesel Particulate Filter (DPF), Selective Catalytic Reduction (SCR), and Diesel Exhaust Fluid (DEF) systems used on all makes of LD, MD, and HD trucks starting in the 2008 model year. Because of the similarities in system operation, this class applies to all makes and models of MD/HD trucks. System operation, service, pattern failures, and maintenance peculiarities will be covered in the class.