This manual covers the Iveco NEF Engine, a line of internal combustion engines designed for robust performance and reliability. Specifically, this service repair manual details the N40 ENT M25, N60 ENT M37, and N60 ENT M40 engine models. Iveco is recognized for its engineering quality, and these engines are built to meet demanding operational requirements, ensuring consistent power delivery and durability in various applications. The purpose of this English-language service repair manual is to provide comprehensive guidance for the repair and maintenance of the Iveco NEF engines. It includes detailed information on technical data, electrical equipment, diagnostics, servicing operations on an installed engine, specialized tools, and complete overhaul procedures. With step-by-step instructions and essential safety regulations, this manual serves as an indispensable resource for owners, mechanics, and technicians to effectively maintain and repair these engines.