Welcome to the comprehensive service manual for the Subaru Impreza WRX STI, covering model years 2004-2005. This performance compact sedan, renowned for its rally heritage and advanced engineering, features an iconic turbocharged boxer engine, Symmetrical All-Wheel Drive with Driver Controlled Center Differential (DCCD), and a performance-tuned suspension. These elements, combined with a potent braking system, make the WRX STI a benchmark in its segment. The GDB chassis variants represent a significant evolution in Subaru's performance offerings, delivering exceptional handling and driving dynamics.

This manual serves as an essential resource for maintaining and repairing your Subaru Impreza WRX STI. It provides in-depth coverage of all major systems, including engine management for the EJ257 engine, drivetrain, suspension, steering, brakes, and electrical systems. You will find detailed procedures for routine maintenance, engine and transmission overhauls, troubleshooting guides, and diagnostic trees. With over 2000 pages of information, this factory service manual empowers owners and technicians with the knowledge required for accurate diagnostics, repairs, and optimal performance, ensuring the longevity and reliability of this celebrated vehicle.