This manual covers the 2006 Subaru Impreza WRX STI, a performance-oriented compact sedan and wagon renowned for its rally-bred engineering. Built on the third generation (GD) chassis, this model is distinguished by its turbocharged 2.5L Boxer engine, delivering 300 horsepower and 290 lb-ft of torque, coupled with a standard 6-speed manual transmission and all-wheel drive system featuring a Driver Controlled Center Differential (DCCD). Its iconic status is cemented by its strong connection to World Rally Championship success and consistent praise for its exceptional handling, acceleration, and all-weather capability, making it a highly sought-after vehicle for performance driving enthusiasts. This comprehensive factory service manual provides detailed guidance for the maintenance, repair, and diagnostics of the 2006 Subaru Impreza WRX STI. Covering mechanical and electrical systems, bodywork, and crucial technical specifications, the manual includes procedures for engine assembly, transmission service, brake and suspension systems, and electrical component troubleshooting. With over 1500 pages of information, it details scheduled maintenance, component disassembly and reassembly, diagnostic trouble codes, and specific fluid requirements, serving as an indispensable resource for owners, mechanics, and technicians to ensure the optimal performance and longevity of their vehicle. 🏷️ Basic Information Identification Make: Subaru Model: Impreza WRX STI Year: 2006 Model Code: GDB Generation Generation Name: Third Generation (GD) Generation Years: 2000-2007 Codes Chassis Code: GDB-F (specific to 2006-2007 model updates) 👋 Introduction Market Position Segment: Performance Compact Sedan/Wagon Reputation: Iconic rally-bred performance car, known for all-wheel drive and turbocharged power Competitive Analysis Key Competitors: Mitsubishi Lancer Evolution, Ford Focus RS, Volkswagen Golf GTI Key Features Performance Focus: Engineered for performance driving, rallying heritage AWD System: Symmetrical All-Wheel Drive with Driver Controlled Center Differential (DCCD) Engine Type: Turbocharged Boxer engine Transmission: Standard 6-speed manual transmission 📋 Manual Details Coverage Areas Primary Coverage: Mechanical, Electrical, Body, Maintenance, Diagnostics Secondary Coverage: Troubleshooting, Wiring Diagrams, Specifications Page Count Estimated Page Count: 1500+ Manual Type Type: Factory Service Manual / Repair Manual Language Language: English Format Format: PDF Download 📖 Manual Coverage Systems Covered Engine Mechanical: Engine assembly, cylinder head, block, lubrication system, cooling system, timing system Engine Performance: Turbocharger system, intercooler, fuel injection, ignition system, emissions control Transmission: 6-speed manual transmission (TY856WB1AA), clutch system, drivetrain (front/rear differentials, DCCD) Brakes: Front and rear brake systems, ABS, parking brake Suspension: Front and rear suspension components, alignment specifications Steering: Power steering system, steering column Electrical: Battery, charging system, starting system, lighting, instruments, accessories, body electrical control units Body: Body structure, exterior panels, interior trim, doors, glass, HVAC system Chassis Electrical: Wiring diagrams, connector pinouts, fuse and relay locations Procedures Included Maintenance: Scheduled maintenance, fluid changes, filter replacements, lubrication points Repair: Component disassembly and reassembly, component testing and replacement Diagnostics: Troubleshooting charts, symptom analysis, diagnostic trouble codes (DTCs) Adjustments: Alignment, clutch, brake adjustments Installation: Major component replacement procedures Technical Depth Depth: Comprehensive; covers basic to advanced repairs and diagnostics Diagnostic Tools: Detailed diagnostic procedures, including use of Subaru Select Monitor (SSM) if applicable 📊 Manual Specifications File Format File Type: PDF Searchable: Yes (typically) Print Quality Quality: High-resolution scans of original factory documents Binding Type Binding: N/A (Digital Download) Paper Type Paper: N/A (Digital Download) ⚙️ Engine Specifications Primary Engine Engine Code: EJ257 Engine Type: 2.5L DOHC Turbocharged Boxer-4 Bore X Stroke: 99.5 mm x 79.0 mm Compression Ratio: 8.0:1 Displacement: 2457 cc Performance Horsepower: 300 hp @ 6000 rpm Torque: 290 lb-ft @ 4000 rpm Fuel System Fuel Delivery: Multi-point Fuel Injection (MPI) Recommended Fuel: Premium Unleaded Gasoline (91+ Octane) Fuel Tank Capacity: 15.1 gallons (57 liters) 🔧 Transmission Standard Transmission Type: 6-speed Manual Transmission Model: TY856WB1AA Optional Optional Transmission: N/A (STI models exclusively manual) Features AWD System: Symmetrical All-Wheel Drive with Driver Controlled Center Differential (DCCD) Dccd Modes: Manual and Automatic modes for center differential lockup Rear Differential: Viscous-coupling Limited-Slip Differential (VLSD) 📐 Dimensions Exterior Length: 173.4 inches (4404 mm) Width: 69.7 inches (1770 mm) Height: 57.7 inches (1465 mm) Wheelbase: 103.1 inches (2619 mm) Ground Clearance: 5.5 inches (140 mm) Weights Curb Weight: Approx. 3285 lbs (1490 kg) Gross Vehicle Weight Rating: Approx. 4355 lbs (1975 kg) Cargo Trunk Capacity: 11.3 cu ft (320 liters) (Sedan), Varies by model (Wagon) 🛡️ Safety Features Ratings NHTSA Front Impact: Not rated or Not Applicable for this specific variant/year in all testing categories IIHS Front Impact: Good (for similar Impreza models of the era) Active Features ABS: Standard Anti-lock Braking System Traction Control: Standard Electronic Stability Control: Not standard on all 2006 WRX STI models, but available or standard on later GD generations. Passive Features Airbags: Front airbags, front side-impact airbags Seatbelts: 3-point front and rear seatbelts with pretensioners Crumple Zones: Front and rear crumple zones for energy absorption 💡 Technology Features Infotainment Audio System: Factory AM/FM/CD player with upgraded speaker system Navigation: Optional factory navigation system Driver Assistance Cruise Control: Standard Connectivity Auxiliary Input: Optional auxiliary input...