R2.8 CM2220 R101B Aftertreatment System Diagrams Section E - Engine and System Identification Page E-17 Aftertreatment System Diagrams Aftertreatment System Views 1 Aftertreatment diesel oxidation catalyst (DOC). To buy Cummins Parts and Service Manuals, Training Guides, or Tools go to our website at https://store.cummins.com