🏷️ Basic Information

Make:

Subaru

Model:

Impreza WRX & STI

Model Variant:

GD/GG Chassis

Model Year:

2004

Chassis Code:

GD (Sedan) / GG (Wagon)

Engine Code Wrx:

EJ205

Engine Code Sti:

EJ257

👋 Introduction

Vehicle Type:

Compact Sports Sedan / Hatchback

Target Audience:

Enthusiast drivers, performance car buyers, rally racing fans

Competitive Segment:

Performance compacts, rallying-inspired homologation specials

Key Competitors:

Mitsubishi Lancer Evolution, Ford Focus RS, Honda Civic Type R (in later generations)

Drivetrain:

Symmetrical All-Wheel Drive (AWD) with front and rear limited-slip differentials (STI) or viscous center differential (WRX)

Engine Philosophy:

Turbocharged Boxer engines known for their low center of gravity and unique sound

Rally Heritage:

Direct lineage to Subaru's dominant World Rally Championship (WRC) cars

📋 Manual Details

Manual Type:

Factory Service Repair Workshop Manual

Language:

English

Format:

Digital (PDF)

Estimated Page Count:

Approx. 2000+ pages (combining WRX and STI specific sections)

Digital Features:

Searchable text, printable pages, high-resolution diagrams

📖 Manual Coverage

Engine Mechanical:

Engine assembly, disassembly, cylinder head, crankshaft, pistons, connecting rods, timing belt, lubrication system, cooling system, fuel injection, ignition system, turbocharger system

Engine Control:

ECU (Engine Control Unit) diagnosis, sensors, actuators, emission controls, evaporative emission control system (EVAP)

Transmission Manual:

Clutch system, 5-speed manual transmission (WRX), 6-speed manual transmission (STI), gearbox overhaul, gear ratios, shift linkage

Transmission AWD:

All-Wheel Drive system (AWD), viscous center differential, rear differential, front differential, power transfer unit (PTU), viscous coupling unit (VCU)

Suspension:

Front suspension (MacPherson strut), rear suspension (double wishbone), springs, shock absorbers, control arms, sway bars, alignment specifications

Brakes:

Front and rear disc brakes, ABS (Anti-lock Braking System), brake hydraulics, caliper specifications, rotor specifications, brake pad replacement

Steering:

Power steering system, steering rack, tie rods, steering column, wheel alignment

Electrical System:

Battery, charging system (alternator), starting system (starter motor), lighting (headlights, taillights, interior), fuses, relays, wiring diagrams, body control module (BCM)

Body And Interior:

Exterior body panels, doors, hood, trunk, interior trim, seats, dashboard, HVAC system, body sealant and rust prevention

Diagnostics Troubleshooting:

Diagnostic Trouble Codes (DTCs), symptom-based troubleshooting, wiring harness testing, component testing

Routine Maintenance:

Oil changes, filter replacements, spark plug replacement, coolant flush, brake fluid flush, air filter replacement

Engine Repair:

Engine rebuild procedures, piston ring replacement, bearing replacement, valve seal replacement, timing belt replacement (critical for EJ series engines)

Transmission Repair:

Transmission overhaul, clutch replacement, differential service, AWD system maintenance

Suspension Steering Repair:

Shock absorber and strut replacement, control arm bushings, ball joint replacement, power steering pump service, wheel bearing replacement

Brake System Repair:

Brake pad and rotor replacement, caliper service, brake line bleeding, ABS module testing

Electrical Troubleshooting:

Use of wiring diagrams, circuit testing, diagnostic tool usage, component replacement (e.g., alternator, starter, sensors)

Bodywork Repair:

Panel alignment, dent repair, rust treatment, trim removal and installation

Depth Level:

Comprehensive factory-level repair and diagnostic information

Diagnostic Focus:

Detailed diagnostic procedures for all major systems, including Subaru Select Monitor (SSM) interaction where applicable

Rebuild Procedures:

Full engine and transmission rebuild specifications and procedures

Torque Specifications:

Detailed torque values for all fasteners and critical components

Wiring Diagrams:

Complete, high-quality, and easily interpretable wiring diagrams for all vehicle systems

📊 Manual Specifications

Digital Format:

PDF

Diagram Quality:

High-quality, detailed diagrams and illustrations

Text Readability:

Clear, concise, and easy-to-read text

Binding Type Digital:

N/A (Digital)

Paper Type Digital:

N/A (Digital)

Text Search:

Fully searchable text for quick information retrieval

⚙️ Engine Specifications

Wrx Engine:

2.0L EJ205 turbocharged flat-four

Sti Engine:

2.5L EJ257 turbocharged flat-four

Wrx Horsepower:

227 hp @ 5600 rpm (approx.)

Wrx Torque:

217 lb-ft @ 4000 rpm (approx.)

Sti Horsepower:

300 hp @ 6000 rpm (approx.)

Sti Torque:

300 lb-ft @ 4000 rpm (approx.)

Fuel Delivery:

Sequential Multi-Port Fuel Injection (MPI)

Fuel Type:

Premium Unleaded Gasoline (91 octane or higher recommended)

Wrx Turbo Type:

TD04L-13T (intercooled)

Sti Turbo Type:

VF39 (intercooled, larger) on US STI

🔧 Transmission

Wrx Transmission:

5-Speed Manual

Sti Transmission:

6-Speed Manual

Optional Transmission:

None for WRX/STI in 2004

AWD System:

Subaru Symmetrical All-Wheel Drive

Sti Center Diff:

Driver Controlled Center Differential (DCCD) - electronically controlled

Manual Transmission Fluid:

Subaru Extra-S Gear Oil (or equivalent API GL-5 75W-90)

📐 Dimensions

Sedan Wheelbase:

104.9 inches

Hatchback Wheelbase:

104.5 inches

Sedan Length:

173.8 inches

Hatchback Length:

174.4 inches

Wrx Curb Weight:

3131 - 3175 lbs (approx.)

Sti Curb Weight:

3285 lbs (approx.)

Wheel Bolt Pattern:

5x100mm

Wrx Tire Size:

215/45R17

Sti Tire Size:

225/45R17 (STI specific tires often used)

🛡️ Safety Features

NHTSA Front Impact:

4-star driver, 5-star passenger (for sedan, general model rating)

IIHS Side Impact:

Acceptable (for sedan, general model rating)

ABS:

Standard (4-wheel ABS)

Traction Control:

Not standard on WRX, but often found on some STI models or aftermarket

Airbags:

Driver and front passenger airbags

Body Structure:

Subaru's Ring-Shaped Reinforcement Frame design

💡 Technology Features

Audio System:

Factory AM/FM/CD player with basic speaker system.

Navigation:

Optional GPS navigation system available on some trims.

Cruise Control:

Standard cruise control

Engine Management:

Sophisticated ECU for engine control and performance optimization.

Connectivity Features:

Limited by modern standards; primarily focused on audio connectivity.

🔧 Maintenance

Oil Change Interval:

Every 3,750 miles or 3.75 months, whichever comes first (severe driving conditions often warrant shorter intervals for performance cars).

Timing Belt Replacement:

Recommended every 105,000 miles or 105 months. Crucial for EJ series engines due to interference design.

Spark Plug Replacement:

NGK Iridium (PFR6G) recommended, typically every 60,000 miles.

Engine Oil Type:

5W-30 or 0W-30 Synthetic, API SN or higher (refer to manual for specific Subaru recommendations)

Coolant Type:

Subaru Super Coolant (Blue) or equivalent long-life coolant

Brake Fluid Type:

DOT 3 or DOT 4

Ej205 Ring Land Failure:

A known weakness in early EJ205 engines, particularly when modified or subjected to high boost, can lead to ring land failure.

Ej257 Piston Slap:

Some EJ257 engines may exhibit piston slap when cold, which is often considered normal but can be a concern for some owners.

Clutch Wear:

Due to the performance nature of the cars, clutch wear can be accelerated with aggressive driving.

Turbocharger Wear:

Turbochargers can be subject to wear over time, especially if maintenance is neglected or if the car is driven hard without proper warm-up/cool-down procedures.

📚 Vehicle History

Subaru Legacy:

Subaru's strong heritage in motorsport, particularly rallying, influences the WRX and STI models.

Gd Gg Generation:

This generation (2002-2007) marked a significant styling and chassis update from the previous GC/GF generation.

Wrx Introduction:

The WRX (World Rally eXperimental) was introduced globally as a homologation special for rally racing, emphasizing performance and AWD.

Sti Introduction:

The STI (Subaru Tecnica International) variant represents a higher-performance, track-focused evolution of the WRX, often featuring more powerful engines, advanced AWD, and chassis enhancements.

Manufacturing Location:

Gunma Plant, Japan

🏆 Awards & Recognition

Car And Driver Щения:

Subaru Impreza WRX and STI models frequently appeared on Car and Driver's '10Best' lists in various years, including the GD/GG generation.

Rally Success:

The Subaru Impreza WRX STI is a legendary name in motorsport, with numerous WRC championships reinforcing its performance credentials.

Enthusiast Following:

Strong aftermarket support and a dedicated enthusiast community contribute to its enduring appeal.