🏷️ Basic Information Identification Make: Subaru Model: Impreza Year: 2004 Trim Level: WRX STI Engine Type: Gasoline Codes Chassis Code: GDB Engine Code: EJ257 👋 Introduction Market Position Segment: Compact Performance Sedan/Hatchback Target Audience: Enthusiast drivers, DIY mechanics, Subaru WRX STI owners Competitive Analysis Competitors: Mitsubishi Lancer Evolution, Ford Focus RS, Volkswagen Golf GTI Key Features Performance Focus: Tuned for high performance, rally heritage All Wheel Drive: Symmetrical All-Wheel Drive system 📋 Manual Details Coverage Areas Primary Coverage: Factory Service Repair Included Sections: Engine, Drivetrain, Chassis, Electrical, Body, HVAC, Maintenance, Troubleshooting Page Count Estimated Pages: Approximately 2000+ Manual Type Type: Service Repair Manual Language Language: English Format Format: Digital (PDF) 📖 Manual Coverage Systems Covered Engine Management: Fuel injection, ignition, emissions control, ECU diagnostics Drivetrain: All-Wheel Drive (AWD) system, differentials, driveshafts, clutch, gearbox Suspension Steering: Front and rear suspension, struts, springs, anti-roll bars, steering rack Brakes: Brake system hydraulics, ABS, rotors, pads, calipers, parking brake Electrical: Wiring diagrams, lighting, power distribution, charging system, starting system, accessories Body Interior: Body panels, doors, windows, seats, interior trim, HVAC system Procedures Included Maintenance: Oil changes, filter replacements, fluid checks and changes, tune-ups, spark plug replacement Diagnostics Troubleshooting: Symptom-based troubleshooting guides, diagnostic trouble codes (DTCs) Repairs: Engine component overhaul, transmission rebuild, brake system repair, suspension component replacement Assembly Disassembly: Detailed steps for removing and installing major components Technical Depth Depth: Comprehensive, from basic maintenance to complete engine and transmission rebuilds Diagnostic Tools: Includes information for using Subaru Select Monitor (SSM) or equivalent OBD-II scanners 📊 Manual Specifications File Format File Type: PDF Searchability: Searchable text for quick information retrieval Print Quality Quality: High-resolution scans with clear diagrams Binding Type Binding: N/A (Digital) Paper Type Paper: N/A (Digital) ⚙️ Engine Specifications Primary Engine Engine Name: 2.5L Turbocharged Boxer (EJ257) Engine Configuration: Flat-four (Boxer) Displacement: 2457 cc Bore X Stroke: 99.5 mm x 79.0 mm Compression Ratio: 8.0:1 Performance Horsepower Us Spec: 300 hp @ 6000 rpm Torque Us Spec: 300 lb-ft @ 4000 rpm Fuel System Fuel Delivery: Multi-point Fuel Injection (MPI), Sequential Turbocharging Fuel Type: Unleaded Premium (91 octane or higher recommended) Turbocharger Turbocharger Type: Twin-scroll IHI VF39 Intercooler Intercooler Type: Top-mount Air-to-Air 🔧 Transmission Standard Transmission Type: 6-speed Manual Gear Ratios: 1st: 3.600, 2nd: 2.275, 3rd: 1.609, 4th: 1.212, 5th: 0.953, 6th: 0.777, Reverse: 3.500 Optional Transmission Type: N/A for WRX STI model Features Center Differential: Viscous coupling limited-slip center differential Rear Differential: Helical limited-slip rear differential Fluid Type Transmission Fluid: API GL-5, SAE 75W-90 synthetic gear oil 📐 Dimensions Exterior Wheelbase: 103.7 inches (2634 mm) Length: 173.8 inches (4415 mm) Width: 68.3 inches (1735 mm) Height: 56.1 inches (1425 mm) Ground Clearance: 5.5 inches (140 mm) Weights Curb Weight: Approx. 3263 lbs (1480 kg) Wheels Tires Wheel Size: 17 x 7.5 inch alloy Tire Size: 225/45R17 Bolt Pattern: 5x114.3 mm (5x4.5 inches) 🛡️ Safety Features Ratings NHTSA Frontal Driver: 5-star NHTSA Frontal Passenger: 5-star IIHS Front Crash Rating: Good IIHS Side Impact Rating: Acceptable Active Features ABS: Standard Anti-lock Braking System (4-wheel disc) Traction Control: Standard Stability Control: Subaru Vehicle Dynamics Control (VDC) - Standard Passive Features Airbags: Front dual-stage airbags, front side-impact airbags Seatbelts: 3-point front and rear seatbelts with pretensioners 💡 Technology Features Infotainment Audio System: Factory AM/FM/CD player with 4-6 speakers (upgradeable) Climate Control: Manual or Automatic Climate Control (depending on trim) Driver Assistance Cruise Control: Standard Connectivity Aux Input: N/A (optional accessory or aftermarket modification) 🔧 Maintenance Service Intervals Oil Change Interval: Every 3,750 miles (6,000 km) or 6 months, whichever comes first (severe duty) Engine Oil Type: API SJ or SL, ILSAC GF-3, SAE 10W-30 synthetic recommended (check owner's manual for specific viscosity) Oil Filter Part Number: Subaru 15208AA031 (example, always verify) Spark Plug Replacement: Every 30,000 miles (48,000 km) Timing Belt Replacement: Not Applicable (EJ257 uses a timing chain) Fluid Specifications Coolant Type: Subaru Super Coolant (or equivalent silicate-free, ethylene glycol based coolant) - Blue Brake Fluid Type: DOT 3 or DOT 4 Fluid Capacities Engine Oil Capacity: 4.8 US quarts (4.5 liters) with filter change Known Issues Common Issue 1: Head gasket leaks (though less prevalent on EJ257 than earlier EJ25s) Common Issue 2: Turbocharger failure (often due to poor oil maintenance or hard driving) Common Issue 3: Clutch wear and failure (especially with aggressive driving) Common Issue 4: Catalytic converter failure (can be heat-related) 📚 Vehicle History Brand Heritage Brand Focus: All-wheel drive, rally racing, practical performance vehicles Model Evolution Generation: GD/GG (2000-2007) Updates 2004: Mid-generation refresh including revised styling, updated suspension tuning, and improved interior. Production Production Location: Gunma Prefecture, Japan 🏆 Awards & Recognition Recognitions Performance Awards: Consistently praised by automotive journalists for its performance and handling Rally Heritage: Strong association with World Rally Championship (WRC) success