🏷️ Basic Information

Make:

Subaru

Model:

Impreza WRX STi

Year:

2004

Chassis Code:

GDB

Engine Code:

EJ207 (JDM/EDM), EJ257 (USDM/CDM)

Generation Name:

Third Generation (GD chassis)

👋 Introduction

Segment:

Performance Compact Sedan/Wagon

Usp:

Iconic rally-bred performance, all-wheel-drive traction, turbocharged Boxer engine, and driver-focused dynamics.

Key Competitors:

Mitsubishi Lancer Evolution, Ford Focus RS, Volkswagen Golf GTI.

Drivetrain:

Subaru's Symmetrical All-Wheel Drive (SAWD) system with Driver Controlled Centre Differential (DCCD).

Engine Layout:

Horizontally-opposed (Boxer) turbocharged engine.

Suspension Geometry:

Performance-tuned suspension for superior handling and grip.

Braking System:

Upgraded Brembo braking system for enhanced stopping power and fade resistance.

📋 Manual Details

Coverage:

All styles and trims for the 2004 Subaru Impreza WRX STi

Page Count:

6,200+

Manual Type:

Service and Repair Manual

Language:

English

Format:

PDF

📖 Manual Coverage

Engine:

Detailed diagnostics, repair, and overhaul procedures for EJ207/EJ257 engines, including turbocharger system, intercooling, fuel injection, ignition, emissions, and engine management.

Transmission:

Comprehensive coverage of the 6-speed manual transmission (TY856WB1CA, TY856WB1CB), including clutch operation, gearbox disassembly/assembly, differential servicing, and driveline components.

Suspension And Steering:

Detailed specifications and procedures for front MacPherson strut and rear multi-link suspension, limited-slip differentials (front and rear DCCD), power steering system, and wheel alignment.

Brakes:

In-depth information on the Brembo braking system, including front 4-piston and rear 2-piston calipers, brake fluid specifications, ABS system diagnostics, and rotor/pad replacement.

Electrical System:

Extensive wiring diagrams, component testing procedures, diagnostic trouble codes (DTCs), fuse box layouts, lighting systems, audio systems, and starter/charging systems.

Body And Chassis:

Procedures for body panel removal/installation, interior trim, glass replacement, underbody protection, and chassis component inspection.

Heating Ventilation And Air Conditioning:

Diagnosis and repair of HVAC system components, refrigerant handling, climate control unit operation, and blower motor/resistor service.

Fuel System:

Fuel pump, injector, fuel filter, and fuel tank service procedures, along with EVAP system diagnosis.

Exhaust System:

Catalytic converter, muffler, and pipe inspection and replacement.

Maintenance:

Scheduled maintenance tasks, fluid changes (oil, coolant, brake fluid, transmission fluid, differential fluid), filter replacements (oil, air, fuel, cabin), spark plug replacement, timing belt inspection/replacement (if applicable to specific EJ variants).

Troubleshooting:

Systematic diagnostic procedures for common and uncommon issues, fault code interpretation, electrical circuit testing, and component diagnosis.

Repair:

Step-by-step instructions for component removal, disassembly, repair, reassembly, and installation for all major vehicle systems.

Diagnostics:

Detailed guidance on using diagnostic tools (OBD-II scanner), interpreting live data, and performing component tests.

Calibration And Adjustment:

Procedures for throttle body cleaning and relearn, idle speed adjustment, and clutch adjustment where applicable.

Depth:

Comprehensive, covering everything from basic fluid checks and tire rotations to complete engine and transmission rebuilds, complex electrical diagnostics, and bodywork repairs.

📊 Manual Specifications

File Format:

PDF

File Size:

310MB

Scan Quality:

Non-scanned, high-resolution digital source

Searchability:

Likely searchable text, enabling quick access to specific information.

Printability:

Printable pages, allowing for physical reference.

Binding Type:

N/A (Digital Format)

Paper Type:

N/A (Digital Format)

⚙️ Engine Specifications

Engine Type:

EJ207 (JDM/EDM) / EJ257 (USDM/CDM) - DOHC, 16-valve, turbocharged Boxer 4-cylinder

Displacement:

2.0 Liters (EJ207) / 2.5 Liters (EJ257)

Horsepower:

Approx. 265-280 hp (JDM EJ207), 265 hp (USDM EJ257), varies by market and specific tune

Torque:

Approx. 250-260 lb-ft (JDM EJ207), 244 lb-ft (USDM EJ257), varies by market and specific tune

Redline:

Typically 7,000 RPM

Fuel Delivery:

Sequential Electronic Fuel Injection (SEFI)

Fuel Type:

Unleaded gasoline (premium recommended/required)

Turbocharger:

IHI VF34 (common for STi), twin-scroll or single-scroll depending on market and spec.

Intercooler:

Top-mounted air-to-air intercooler.

🔧 Transmission

Transmission Type:

6-speed Manual

Transmission Model:

TY856WB1CA (JDM), TY856WB1CB (USDM/CDM)

Optional Transmission:

None (All 2004 WRX STi models were 6-speed manual)

Dccd:

Driver Controlled Centre Differential (DCCD) with manual and automatic modes.

Differentials:

Front Helical Limited Slip Differential (LSD), Rear Helical Limited Slip Differential (LSD).

📐 Dimensions

Length:

Approx. 4,405 mm (173.4 in)

Width:

Approx. 1,740 mm (68.5 in)

Height:

Approx. 1,440 mm (56.7 in)

Wheelbase:

Approx. 2,510 mm (98.8 in)

Track Width Front:

Approx. 1,470 mm (57.9 in)

Track Width Rear:

Approx. 1,470 mm (57.9 in)

Ground Clearance:

Approx. 135 mm (5.3 in)

Curb Weight:

Approx. 1,440 - 1,470 kg (3,175 - 3,240 lbs)

Gross Vehicle Weight Rating:

Typically around 1,900 kg (4,189 lbs)

🛡️ Safety Features

NHTSA Crash Test Ratings:

Likely not directly rated by NHTSA for the specific STi variant; base Impreza models received mixed ratings.

ABS:

Standard Anti-lock Braking System (ABS).

Traction Control:

Standard Traction Control System (TCS) and Vehicle Stability Control (VSC).

Airbags:

Driver and front passenger airbags, side curtain airbags (availability may vary by market).

Seatbelts:

3-point seatbelts with pretensioners.

Body Structure:

Reinforced safety cage and crumple zones.

💡 Technology Features

Head Unit:

Factory AM/FM/CD player, often with basic display and auxiliary input (depending on trim/market).

Speaker System:

Standard 4-6 speaker system.

Cruise Control:

Standard cruise control.

Auxiliary Input:

Optional auxiliary input jack for audio devices.

🔧 Maintenance

Oil Change Interval:

Typically every 3,750 miles (6,000 km) or 6 months, using synthetic oil. Consult manual for exact recommendation.

Air Filter Replacement:

Every 15,000 miles (24,000 km) or as needed based on driving conditions.

Spark Plug Replacement:

Typically every 30,000 - 60,000 miles (48,000 - 96,000 km) depending on spark plug type (e.g., iridium).

Timing Belt Replacement:

Not applicable for EJ207/EJ257 engines as they use a timing chain. However, the timing belt driving auxiliary components like the oil pump is present and needs inspection/replacement at intervals outlined in the manual, typically around 100,000 miles (160,000 km).

Engine Oil Type:

SAE 5W-30 or 10W-30 Synthetic, API SG/SH/SJ or ILSAC GF-2/GF-3 rated. Consult manual for specific viscosity based on ambient temperature.

Coolant Type:

Subaru Super Coolant (Blue) or equivalent ethylene glycol-based coolant with corrosion inhibitors.

Transmission Fluid Type:

API GL-4 or GL-5 gear oil, SAE 75W-90. Consult manual for exact specifications for front and rear differentials.

Brake Fluid Type:

DOT 3 or DOT 4 brake fluid.

Power Steering Fluid:

Subaru Automatic Transmission Fluid (ATF) or equivalent.

Ring Land Failure:

A known potential issue in some EJ257 engines, particularly those modified or driven hard, leading to piston ring land cracking. Proper engine management and fuel are critical.

Clutch Wear:

Can be accelerated by aggressive driving or frequent launches.

Head Gasket Leaks:

Less common on EJ207/EJ257 compared to earlier Subaru engines, but still a potential issue that requires prompt attention if detected.

Catalytic Converter Failure:

Can occur due to rich fuel conditions or prolonged misfires.

📚 Vehicle History

Rally Heritage:

Subaru's extensive success in the World Rally Championship (WRC) heavily influenced the development of the WRX and STi models.

Third Generation Introduction:

The GD chassis Impreza WRX STi marked a significant evolution from the previous GC chassis, featuring a wider body, updated chassis dynamics, and distinct styling.

Jdm Vs Usdm:

The 2004 model year was particularly significant as it saw the first official import of the WRX STi to the North American market, albeit with the EJ257 engine instead of the JDM's EJ207.

Production Location:

Mainly manufactured in Japan.

Production Period:

2002-2007 (GD chassis generation)

🏆 Awards & Recognition

Car And Driver 10Best:

The Subaru Impreza WRX (non-STi) was a frequent recipient of Car and Driver's '10Best' list during this era, highlighting its performance and value proposition, which extended to the STi.

Rally Championships:

The STi badge inherently carries the prestige of Subaru's multiple WRC manufacturer and driver championships.