🏷️ Basic Information

Make:

Subaru

Model:

Impreza

Year:

2004

Body Style:

Sedan, Wagon

Generation Name:

Second Generation (GD/GG)

Generation Years:

2000-2007

Chassis Codes:

GD (Sedan), GG (Wagon)

Engine Codes:

EJ201, EJ202, EJ251, EJ253, EJ205 (WRX), EJ255 (WRX STI)

👋 Introduction

Vehicle Segment:

Compact car, rally-inspired performance variant.

Target Audience:

Enthusiasts, DIY mechanics, Subaru owners seeking in-depth repair knowledge.

Competitors:

Honda Civic, Toyota Corolla, Mazda3, Mitsubishi Lancer.

Distinguishing Features:

Standard Symmetrical All-Wheel Drive (AWD), strong performance variants (WRX, STI), rally heritage.

Vehicle Strengths:

AWD capability, agile handling, robust engine options (especially turbo variants), practical interior.

Manual Value Proposition:

Empowers owners to perform detailed maintenance and repairs, saving costs and understanding their vehicle thoroughly.

📋 Manual Details

Primary Coverage:

Full service and repair instructions for 2004 Subaru Impreza.

Engine Coverage:

2.0L Naturally Aspirated (EJ20), 2.5L Naturally Aspirated (EJ25), 2.0L Turbocharged (EJ205), 2.5L Turbocharged (EJ255/EJ257 - WRX/STI variants)

Transmission Coverage:

5-Speed Manual, 4-Speed Automatic

Chassis Coverage:

Suspension, Steering, Brakes, Body

Electrical Coverage:

Wiring diagrams, electrical components, diagnostics

Estimated Pages:

1500+

Type:

Service Repair Workshop Manual

Language:

English

Format:

Digital (PDF)

📖 Manual Coverage

Engine Mechanical:

Engine assembly, disassembly, cylinder head, pistons, crankshaft, camshafts, timing belt/chain, lubrication system, cooling system.

Engine Performance:

Fuel injection system, ignition system, emission control systems (EVAP, secondary air injection), turbocharger system (where applicable).

Transmission Manual:

Clutch system, 5-speed transmission (disassembly, assembly, gear ratios, synchronizers).

Transmission Automatic:

4-speed automatic transmission (ATF specifications, torque converter, valve body, planetary gear sets, maintenance).

Drivetrain:

All-Wheel Drive (AWD) system, front differential, rear differential, driveshafts, CV joints.

Suspension:

Front struts, rear shock absorbers, control arms, sway bars, bushings, wheel bearings.

Steering:

Power steering system (pump, rack and pinion, fluid), steering column, tie rods.

Brakes:

Front and rear disc brakes, ABS system, brake fluid specifications, hydraulic lines, parking brake.

Electrical System:

Battery, alternator, starter motor, lighting system, interior electrical components, fuses, relays, ECU/ECM.

HVAC:

Air conditioning system, heater core, blower motor, climate control components.

Body And Frame:

Body panel removal and installation, interior trim, doors, windows, bumpers, chassis specifications.

Maintenance:

Oil changes, filter replacements, spark plug replacement, fluid checks and top-offs, tire rotation, brake pad replacement.

Troubleshooting:

Diagnostic trouble codes (DTCs), symptom-based troubleshooting for common issues, electrical system diagnostics.

Major Repairs:

Engine rebuilds, transmission overhaul, suspension component replacement, brake system bleeding, clutch replacement.

Diagnostics:

OBD-II diagnostics, sensor testing, actuator testing, wiring diagram interpretation.

Wheel Alignment:

Specifications for camber, caster, toe for front and rear suspension.

Wiring Diagrams:

Detailed, system-specific wiring schematics for all major electrical components.

Depth:

Comprehensive from basic maintenance to complete engine and transmission rebuilds, including detailed electrical diagnostics and troubleshooting.

Diagnostic Tools:

Guidance on using scan tools and multimeters for diagnosis.

Torque Specifications:

Precise torque values for all critical fasteners.

Special Tools:

Identification and use of Subaru-specific special tools required for certain procedures.

📊 Manual Specifications

Type:

Searchable PDF

Quality:

High-resolution scans, clear text and diagrams.

Printability:

Printable pages

Binding:

N/A (Digital Product)

Paper:

N/A (Digital Product)

⚙️ Engine Specifications

Engine Options:

2.0L EJ20, 2.5L EJ25 (Naturally Aspirated); 2.0L EJ205 Turbo (WRX); 2.5L EJ255/EJ257 Turbo (WRX STI).

2.5L Na Horsepower:

Approx. 165-173 hp (EJ251/EJ253)

2.5L Na Torque:

Approx. 166-177 lb-ft (EJ251/EJ253)

Wrx Horsepower:

Approx. 227 hp (EJ205)

Wrx Torque:

Approx. 217 lb-ft (EJ205)

Sti Horsepower:

Approx. 300 hp (EJ257)

Sti Torque:

Approx. 300 lb-ft (EJ257)

Injection Type:

Multi-point Fuel Injection (MPI) / Sequential Electronic Fuel Injection (SEFI)

Fuel Type:

Unleaded gasoline (91 octane or higher recommended for turbo models)

Timing Mechanism:

Timing belt (EJ20/EJ25 naturally aspirated), timing belt (EJ205 WRX), timing belt (EJ255/EJ257 WRX STI)

🔧 Transmission

Transmission Type:

5-Speed Manual Transmission

Transmission Type:

4-Speed Automatic Transmission

AWD System:

Symmetrical All-Wheel Drive (AWD) with Active Torque Split (ATS) or Variable Torque Distribution (VTD) on certain models.

Clutch Type:

Hydraulically actuated, single dry plate.

Manual Transmission Fluid:

Subaru Genuine Gear Oil (GL-5 75W-90) or equivalent.

Automatic Transmission Fluid:

Subaru Genuine ATF HP or Dexron III/Mercon compatible fluid.

📐 Dimensions

Length Sedan:

Approx. 177.7 inches (4515 mm)

Length Wagon:

Approx. 173.8 inches (4415 mm)

Width:

Approx. 68.7 inches (1745 mm)

Height:

Approx. 56.7 inches (1440 mm) for Sedan, 57.1 inches (1450 mm) for Wagon

Wheelbase:

Approx. 104.0 inches (2640 mm)

Ground Clearance:

Approx. 6.1 inches (155 mm)

Curb Weight:

Approx. 2900-3200 lbs (1315-1450 kg), varies by trim and drivetrain.

Towing Capacity:

Not typically recommended or specified for this model.

Cargo Volume Sedan:

Approx. 11.7 cu ft

Cargo Volume Wagon:

Approx. 30.4 cu ft (rear seats up)

🛡️ Safety Features

NHTSA Front Impact:

5 Stars (Driver), 4 Stars (Passenger)

IIHS Side Impact:

Good

ABS:

Standard Anti-lock Braking System (ABS).

AWD:

Standard Symmetrical All-Wheel Drive for enhanced traction.

Traction Control:

Available on select models.

Airbags:

Front airbags, available side-impact airbags.

Seatbelts:

Three-point seatbelts with pre-tensioners.

Child Seat Anchors:

LATCH (Lower Anchors and Tethers for Children) system.

💡 Technology Features

Audio System:

Factory AM/FM/CD player, optional premium audio systems.

Display:

Basic digital display for clock and audio.

Cruise Control:

Standard on most trims.

All Wheel Drive:

Core technology providing enhanced traction and stability.

Auxiliary Input:

Typically not standard; aftermarket solutions available.

Bluetooth:

Not available on factory systems for this model year.

🔧 Maintenance

Oil Change Interval:

Every 3,750 miles or 6 months (severe driving), or 7,500 miles or 12 months (normal driving), consult owner's manual.

Engine Air Filter:

Replace every 30,000 miles or 24 months.

Cabin Air Filter:

Replace every 15,000 miles or 12 months.

Spark Plugs:

Replace every 60,000 miles (Iridium type) or 30,000 miles (copper type).

Timing Belt:

Replace every 105,000 miles or 105 months. Crucial for engine longevity.

Engine Oil:

5W-30 (API SG, SH, or SJ classification) for naturally aspirated; 5W-30 (API SG, SH, SJ, or SL) for turbo models.

Coolant:

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

Brake Fluid:

DOT 3 or DOT 4.

Power Steering Fluid:

Subaru Genuine Power Steering Fluid or Dexron II/III compatible fluid.

Head Gaskets:

While less common on EJ253 compared to earlier EJ25s, head gasket leaks can still occur, especially with higher mileage or overheating.

Turbo Wear:

For WRX/STI models, regular oil changes and proper cool-down procedures are vital to prevent turbocharger wear.

Clutch Wear:

Clutch wear is dependent on driving style, but can be a wear item.

Suspension Bushings:

Rubber suspension bushings can degrade over time, leading to clunks or vague handling.

Oxygen Sensors:

Oxygen sensors can fail over time, affecting fuel economy and emissions.

📚 Vehicle History

Manufacturer:

Subaru Corporation, Japan.

Philosophy:

Known for Symmetrical All-Wheel Drive and horizontally-opposed (Boxer) engines.

Impreza Lineage:

Introduced globally in 1992 as a compact car, evolving through multiple generations with a focus on AWD and performance variants.

Second Gen Redesign:

The 2004 model year represents a mid-cycle refresh for the second generation (GD/GG chassis), which debuted for the 2002 model year. Key changes included updated styling (especially the front fascia and headlights) and minor mechanical revisions.

Manufacturing Locations:

Japan (primarily Gunma Plant).

Sales Figures:

Consistent strong sales in North America, especially among AWD enthusiasts.

🏆 Awards & Recognition

IIHS Top Safety Pick:

While specific year recognition varies, the Impreza's safety design was generally well-regarded.

Car And Driver 10Best:

The WRX variant was a frequent contender and recipient of Car and Driver's 10Best list in various years, highlighting its performance.

Emissions Compliance:

Meets EPA and California LEV (Low Emission Vehicle) standards for its respective model year.