This manual covers the Iveco NEF Engine N40 ENT M25, a robust engine designed for a variety of applications. Engineered for durability and performance, this engine is built to meet the demands of maintenance, repair, rebuilding, refurbishing, and restoration. Its construction emphasizes reliability, ensuring consistent operation across its intended service life. The purpose of this Factory Service Repair Manual is to provide comprehensive guidance for the Iveco NEF Engine N40 ENT M25. It includes detailed step-by-step repair procedures, advanced troubleshooting, and all diagnostic procedures, supported by necessary illustrations, diagrams, and photos. The manual also covers essential maintenance checklists, servicing specifications, tightening torques, and procedures for various systems including the cooling system, fuel filter, electrical system, alternator, and regulator, along with special tools information.