This workshop service manual covers the Mercury Mariner outboard motor manufactured between the years 2002 and 2005. This particular generation of Mariner motors is recognized for its robust engineering and reliable performance, featuring a 30 HP, 4-stroke engine with Electronic Fuel Injection (EFI) and a water-cooled system. The outboard lower unit gearcase is designed for efficient power transfer. This manual is specifically tailored to provide comprehensive information for these models, ensuring owners can maintain their investment. The purpose of this English-language manual is to serve as an authoritative guide for the maintenance, repair, and troubleshooting of your Mercury Mariner outboard motor. It details essential procedures, including lubrication specifications, service intervals for critical components like spark plugs and water pump impellers, and diagnostics for common starting, running, and electrical issues. With 583 pages of detailed information, this resource is indispensable for owners and technicians alike, enabling them to keep the engine operating at peak efficiency and longevity.