This Workshop Service Repair Manual covers Iveco Motors NEF series internal combustion engines, specifically the N45 (4.5L) and N67 (6.7L) engine models. These engines are designed to meet Tier 3 emission standards and are engineered for robust performance and reliability in various applications. The manual provides comprehensive information for the N45, N45 ENT.X, N45 MSS.X, N45 MNS.X, N45 MST.X, N45 MNT.X, N67, N67 ENT.X, N67 ERT.X, N67 MRT.X, N67 MNT.X, NEF F4HE (Part 1), NEF F4CE (Part 2), NEF F4DE (Part 3), and NEF F4GE (Part 4) engine variants, ensuring detailed support for a wide range of configurations. The purpose of this manual is to assist owners, mechanics, and technicians in the service and repair of these Iveco Motors engines. It includes detailed sections on overview, technical data, electrical equipment, diagnostics, maintenance, servicing operations on the installed engine, specialized tools, engine overhaul procedures, and essential safety regulations. The high focus on DIY repair support ensures that users can effectively maintain and troubleshoot their engines, promoting longevity and optimal performance.