🏷️ Basic Information

Make:

Subaru

Model:

Impreza (STI)

Model Code:

GDB

Product Name:

2003 2004 Subaru Impreza (STI) Workshop Service Repair Manual

Generation Code:

GD/GG

Generation Years:

2000-2007 (GD/GG)

Chassis Code Gdb:

GDB

👋 Introduction

Segment:

Performance Compact Sedan/Wagon

Target Audience:

Enthusiasts, rally fans, performance car owners seeking detailed repair information

Key Competitors Era:

Mitsubishi Lancer Evolution, Ford Focus RS, Volkswagen Golf GTI/R32

Performance Focus:

Iconic turbocharged boxer engine, Symmetrical All-Wheel Drive (AWD) system, performance-tuned suspension and brakes

Rally Heritage:

Directly derived from Subaru's World Rally Championship (WRC) success

📋 Manual Details

Years Covered:

2003, 2004

Models Covered:

Subaru Impreza WRX STI

Regions Covered:

Global (specific to WRX STI variants)

Estimated Pages:

Over 2000 pages (typical for comprehensive workshop manuals)

Type:

Workshop Service Repair Manual

Language:

English

Format:

Digital (likely PDF)

📖 Manual Coverage

Engine:

EJ257 Turbocharged Boxer Engine (Full overhaul, diagnostics, timing belt, cooling, lubrication, fuel, ignition, emissions)

Transmission:

6-Speed Manual Transmission (TY856WB1AA) (Clutch, gearbox overhaul, drivetrain, differentials, AWD system)

Suspension:

Front McPherson Strut, Rear Independent Double Wishbone (Springs, struts, bushings, alignment procedures, hub assemblies)

Brakes:

Front 4-Piston (Brembo), Rear 2-Piston (Brembo) (Brake fluid, calipers, rotors, lines, ABS system)

Electrical:

Wiring diagrams, ECU diagnostics, lighting, power windows, audio system, instrument cluster, starter, alternator

Body And Chassis:

Frame, panels, doors, hood, trunk, interior trim, glass replacement, rust repair

Climate Control:

HVAC system (compressor, condenser, evaporator, heater core, refrigerant, blower motor)

Fuel System:

Fuel pump, injectors, fuel filter, fuel lines, EVAP system

Cooling System:

Radiator, hoses, thermostat, water pump, coolant specifications

Exhaust System:

Manifolds, catalytic converter, mufflers, pipes, gaskets

Steering:

Power steering system, steering column, rack and pinion

Maintenance:

Scheduled maintenance, oil changes, filter replacements, brake fluid flush, coolant flush, spark plug replacement

Diagnostics:

Troubleshooting charts, DTC code interpretation, sensor testing, component testing

Repair:

Component removal and installation, engine rebuild, transmission overhaul, suspension component replacement, body panel repair

Installation:

Component upgrades (e.g., turbocharger, intercooler - though focus is OEM), accessory installation

Specifications:

Torque specifications, clearances, tolerances, fluid capacities, wiring diagrams

Depth:

Comprehensive (from basic maintenance to full engine and transmission rebuilds, including electrical diagnostics)

Diagnostic Tools:

Information applicable to Subaru Select Monitor (SSM) or OBD-II scan tools

Special Tools:

References to Subaru-specific special tools for various procedures (e.g., timing belt tensioner tool, injector puller)

📊 Manual Specifications

Digital Format:

PDF (Searchable text is highly probable for quality manuals)

Resolution:

High-resolution scans ensuring clarity of diagrams and text

Digital Binding:

N/A (Digital format)

Digital Paper Type:

N/A (Digital format)

Completeness Claim:

100% Complete (as per product description, implying no missing sections)

⚙️ Engine Specifications

Engine Code:

EJ257

Engine Type:

DOHC 16-valve turbocharged boxer-4

Displacement:

2457 cc (2.5 Liters)

Horsepower Usdm:

265 hp @ 5600 rpm (approx.)

Torque Usdm:

247 lb-ft @ 3600 rpm (approx.)

Compression Ratio:

8.0:1

Turbocharger:

IHI VF39 (water-cooled, ball-bearing)

Intercooler:

Top-mounted air-to-air

Fuel Delivery:

Multi-point fuel injection (MPFI)

Fuel Type:

Unleaded gasoline (91 octane or higher recommended)

Throttle Body:

Drive-by-wire (electronic throttle control)

🔧 Transmission

Type:

6-Speed Manual Transmission

Model Code:

TY856WB1AA

Type:

N/A (STI was manual-only)

Drivetrain:

Symmetrical All-Wheel Drive (AWD) with Driver Controlled Center Differential (DCCD)

Differentials:

Front Helical LSD, Rear Helical LSD, DCCD Center Diff

Gear Ratios:

Refer to manual for specific ratios (6-speed specific ratios)

📐 Dimensions

Wheelbase:

2525 mm (99.4 in)

Length:

4405 mm (173.4 in)

Width:

1770 mm (69.7 in)

Height:

1410 mm (55.5 in)

Ground Clearance:

135 mm (5.3 in)

Curb Weight:

Approx. 1470 kg (3240 lbs)

Gross Vehicle Weight Rating:

Refer to vehicle placard

Trunk Volume:

Refer to manual (varies by body style - sedan/wagon)

🛡️ Safety Features

NHTSA Front Impact:

4/5 Stars (for comparable 2003-2004 models)

NHTSA Side Impact:

4/5 Stars (for comparable 2003-2004 models)

IIHS Frontal Offset:

Good (for comparable 2003-2004 models)

ABS:

Standard (4-wheel ABS with EBD)

Traction Control:

Subaru Vehicle Dynamics Control (VDC) available on some models/trims

AWD:

Symmetrical All-Wheel Drive (standard)

Airbags:

Front dual-stage airbags, front side-impact airbags

Seatbelts:

3-point seatbelts with pretensioners and force limiters

Child Anchors:

LATCH (Lower Anchors and Tethers for Children) system

💡 Technology Features

Head Unit:

Factory fitted AM/FM stereo with CD player. Aftermarket options are common.

Speaker System:

Standard speaker configuration, often with front tweeters. Upgrades are popular.

Cruise Control:

Standard

Anti Lock Brakes:

Standard (4-wheel ABS)

Stability Control:

Subaru Vehicle Dynamics Control (VDC) optional or standard on some trims.

Auxiliary Input:

Rarely standard on factory units, often an aftermarket addition.

🔧 Maintenance

Oil Change Interval:

Every 3,750 miles or 6 months (severe use), 7,500 miles or 12 months (normal use) - refer to manual for exact specification based on driving conditions.

Timing Belt Replacement:

105,000 miles or 105 months (critical replacement interval, often recommended with water pump and tensioner).

Transmission Fluid Change:

Every 30,000 miles or 36 months (manual transmission, AWD components - refer to manual for precise intervals).

Coolant Flush:

Every 30,000 miles or 36 months.

Engine Oil Type:

SAE 5W-30 Synthetic (API SG, SH, SJ, SL, or SM rated) - check manual for specific API classification and viscosity for climate.

Engine Oil Capacity:

4.5 US quarts (4.3 L) with filter change

Brake Fluid Type:

DOT 3 or DOT 4 (refer to manual for specific recommendation)

Power Steering Fluid Type:

Subaru/Dexron II or equivalent

Coolant Type:

Subaru Super Coolant (Blue) or equivalent (50/50 mix with distilled water)

Piston Ring Land Failure:

Common in early EJ25 engines, especially with aggressive tuning, but the EJ257 in the STI is generally more robust. Still, vigilant maintenance and proper fueling are key.

Head Gasket Leaks:

Less common on the EJ257 compared to earlier EJ25s, but still a potential issue if overheated or improperly maintained.

Clutch Wear:

Can be accelerated by aggressive driving or frequent hard launches.

Turbocharger Wear:

The VF39 can develop issues if oil starvation or contamination occurs. Regular oil changes are crucial.

Rear Differential Noise:

Occasional reports of differential noise, often related to fluid degradation or wear.

📚 Vehicle History

Subaru Motorsports:

Long and successful history in rallying, particularly with the Impreza platform (Prodrive era).

Gd Gg Generation:

Introduced in 2000, the GD/GG generation marked a significant design departure with a more rounded, less angular look compared to the GC/GF generation. The STI variant was significantly enhanced for performance.

Predecessor:

Subaru Impreza WRX STI (GC/GF generation)

Manufacturing Plant:

Gunma Manufacturing Plant, Japan

Production Years Model:

2000-2007 (GD/GG generation)

🏆 Awards & Recognition

Car And Driver Ten Best:

The Impreza WRX (non-STI) was a frequent recipient of Car and Driver's '10Best' list during this era, highlighting the platform's overall quality and performance.

Sport Compact Car:

Often praised by enthusiast publications for its rally-bred performance and AWD capabilities.