The Cummins Engine Management System (EMS), centered on the Electronic Control Module (ECM), uses sensors (CKP, MAP, EGT, etc.) to monitor engine conditions and commands actuators (injectors, VGT, EGR) for precise control. It optimizes air-fuel ratios, manages emissions aftertreatment, and ensures engine protection, enabling performance, fuel efficiency, and emissions compliance. Understanding its architecture is key for diagnostics and maintenance.