The Mercury Mariner 225 EFI outboard motor, designed for a wide range of marine applications, exemplifies robust engineering and reliable performance. Featuring an inline 6-cylinder engine with 3.0 liters of displacement and Electronic Fuel Injection (EFI), this motor delivers 225 horsepower. Its water-cooled system, CDI ignition, and power trim and tilt capabilities ensure efficient operation and user convenience. Built for durability and consistent power output, the 225 EFI is engineered to meet the demands of both recreational and professional boating. This Service Repair Manual provides comprehensive guidance for the maintenance and repair of the Mercury Mariner 225 EFI outboard motor, serial number range 0T409000 & Above. It covers essential procedures including routine maintenance, lubrication, ignition system servicing, and troubleshooting common issues. Detailed technical specifications, diagrams, and safety guidelines are included to assist owners, technicians, and mechanics in preserving the optimal performance and longevity of their Mercury Mariner outboard.