The Mercury Mariner 225 HP Optimax DFI represents a significant advancement in outboard engine technology, designed for demanding marine applications. This service manual covers models produced from a specific serial number range, beginning with US serial number 0G386496 and above. Engineered for reliability and performance, the Optimax DFI series is renowned for its direct fuel injection system, offering enhanced fuel efficiency and power output. This manual is an essential resource for understanding and maintaining the sophisticated systems that contribute to the engine's robust operation.

This comprehensive service manual provides detailed instructions for all aspects of maintenance and repair for the Mercury Mariner 225 HP Optimax DFI. It includes step-by-step procedures for installation, removal, disassembly, assembly, and diagnostic checks. The manual is structured to be a user-friendly reference for both professional mechanics and experienced DIY enthusiasts. Its purpose is to ensure that owners and technicians have the necessary information to keep the engine in optimal working condition, covering all technical specifications and essential repair guidelines.