🏷️ Basic Information

Make:

Subaru

Model:

Impreza WRX STI

Generation:

Third Generation (GR/GH/GE/GV/GVB)

Model Years Covered:

2006-2007

Chassis Codes:

GVB (Hatchback), GVF (Sedan)

Engine Codes Primary:

EJ257

👋 Introduction

Segment:

Performance Compact / Rally Homologation Special

Target Audience:

Enthusiasts, performance drivers, rally fans, tuners, and owners seeking in-depth maintenance and repair knowledge.

Competitors:

Mitsubishi Lancer Evolution, Honda Civic Type R, Ford Focus RS

Performance Focus:

Engineered for high-performance driving with advanced AWD, powerful turbocharged engine, and sophisticated suspension.

Rally Heritage:

Direct descendant of Subaru's WRC (World Rally Championship) lineage, offering a potent combination of power, handling, and durability.

Driver Engagement:

Emphasis on driver feedback and control, with a communicative steering system and a robust manual transmission.

📋 Manual Details

Engine:

Yes

Transmission:

Yes

Drivetrain:

Yes

Suspension:

Yes

Brakes:

Yes

Steering:

Yes

Electrical System:

Yes

HVAC:

Yes

Body And Trim:

Yes

Interior:

Yes

Diagnostics And Troubleshooting:

Yes

Wiring Diagrams:

Yes

Torque Specifications:

Yes

Tightening Sequences:

Yes

Maintenance Schedule:

Yes

Fluid Capacities:

Yes

Component Locations:

Yes

Estimated Pages:

> 2000 (typical for comprehensive manuals of this era)

Type:

Factory Service Manual / Repair Manual

Language:

English

Format:

PDF

📖 Manual Coverage

Engine Mechanical:

Detailed disassembly, inspection, and reassembly of EJ257 boxer engine, including cylinder heads, pistons, crankshaft, connecting rods, timing belt system, and lubrication system.

Engine Management:

ECU (Engine Control Unit) operation, sensor inputs (MAF, MAP, O2, Knock, Cam/Crank position), fuel injection strategy, ignition timing control, and emissions control systems.

Turbocharger And Intercooler:

Removal, inspection, and installation of the TD04 turbocharger, blow-off valve (BOV), wastegate actuator, and top-mount intercooler system, including boost pressure control.

Transmission Manual:

Detailed procedures for the 6-speed manual transmission (TY856), including clutch replacement, gearbox disassembly, inspection of gears, synchronizers, and shift mechanisms.

Drivetrain AWD:

Subaru's Symmetrical All-Wheel Drive system, including front and rear differentials, center differential operation (DCCD - Driver's Control Center Differential for STI), driveshafts, and wheel hubs.

Suspension And Steering:

Front and rear suspension components (struts, springs, control arms, sway bars), steering rack, power steering system, wheel alignment specifications, and strut tower brace.

Braking System:

Brake system components including Brembo calipers (front and rear), brake pads, rotors, brake lines, master cylinder, ABS (Anti-lock Braking System) module, and parking brake.

Electrical And Electronics:

Full wiring diagrams, fuse box layouts, lighting systems, power windows, central locking, instrument cluster, audio system, and ECU pinouts.

HVAC System:

Air conditioning system operation, refrigerant, compressor, condenser, evaporator, heater core, and climate control module.

Body And Exterior:

Body panel removal and installation, door mechanisms, hood, trunk/tailgate, bumpers, fenders, spoilers, and exterior trim.

Interior Trim:

Dashboard removal, seat removal and installation, door panel trim, headliner, and interior lighting.

Routine Maintenance:

Oil changes, filter replacements (oil, air, cabin), spark plug replacement, brake fluid flush, coolant replacement, and drive belt inspection/replacement.

Component Replacement:

Detailed step-by-step instructions for replacing virtually all major and minor components within the vehicle.

Troubleshooting Guides:

Systematic diagnostic procedures for identifying and resolving common and uncommon vehicle issues, often including symptom-based troubleshooting trees.

Rebuild Procedures:

Comprehensive instructions for rebuilding major sub-assemblies like the engine, transmission, and differentials.

Diagnostic Tools Usage:

Information on using Subaru's Select Monitor (SSM) or equivalent diagnostic tools for reading trouble codes and accessing live data.

Specifications Data:

Precise torque values for all fasteners, critical component clearances, fluid specifications, and wear limits.

Depth:

Comprehensive: Covers everything from basic fluid checks to complete engine and transmission overhauls. Suitable for professional mechanics and dedicated enthusiasts.

📊 Manual Specifications

File Type:

Searchable PDF

Printability:

Printable pages

Image Resolution:

High-resolution images, diagrams, and schematics for clarity

Binding:

N/A (Digital PDF)

Paper Quality:

N/A (Digital PDF)

⚙️ Engine Specifications

Engine Code:

EJ257

Engine Type:

2.5L DOHC 16-valve turbocharged flat-four (Boxer)

Bore X Stroke:

99.5 mm x 79.0 mm

Compression Ratio:

8.2:1

Horsepower:

300 hp @ 6200 rpm

Torque:

330 lb-ft (447 Nm) @ 4000 rpm

Fuel Delivery:

Sequential Multi-Port Fuel Injection (S-MPI) with Electronic Throttle Control (ETC)

Fuel Type Required:

Premium Unleaded Gasoline (91 octane or higher recommended)

Engine Control Unit:

ECU: Denso / Hitachi (specifics may vary by market)

Turbocharger Model:

IHI VF39 (twin-scroll)

Intercooler Type:

Top-mount air-to-air intercooler

🔧 Transmission

Transmission Type:

6-speed Manual Transmission (TY856)

Optional Transmission:

N/A for WRX STI models of this generation

All Wheel Drive:

Symmetrical All-Wheel Drive with Driver's Control Center Differential (DCCD)

Dccd Modes:

Manual (16-step) and Auto modes for center differential locking

Manual Transmission Fluid:

Subaru Extra-S Gear Oil (75W-90 GL-5) or equivalent API GL-5, SAE 75W-90 synthetic gear oil

📐 Dimensions

Length:

4415 mm (Hatchback) / 4580 mm (Sedan)

Width:

1795 mm

Height:

1475 mm (Hatchback) / 1465 mm (Sedan)

Wheelbase:

2625 mm

Wheel Bolt Pattern:

5x114.3 mm

Wheel Size Standard:

18 x 8.5 inches

Tire Size Standard:

225/40R18

Curb Weight:

Approximately 1500 kg (3307 lbs)

🛡️ Safety Features

NHTSA Front Impact:

5-Star (for 2006-2007 Impreza models)

NHTSA Side Impact:

5-Star (for 2006-2007 Impreza models)

IIHS Moderate Overlap Front:

Good (for 2006-2007 Impreza models)

ABS:

Standard Anti-lock Braking System

Traction Control:

Standard Traction Control System (TCS)

Electronic Stability Control:

Standard Electronic Stability Control (VDC - Vehicle Dynamics Control)

Airbags:

Driver and front passenger airbags, front side-impact airbags, side-curtain airbags (depending on trim/market)

Seatbelts:

3-point height-adjustable front seatbelts with pretensioners, rear 3-point seatbelts

Body Structure:

Advanced Supplemental Restraint System (SRS) and Subaru's proprietary Ring-Shaped Reinforcement Frame

💡 Technology Features

Head Unit:

Factory single-DIN or double-DIN head unit with AM/FM/CD, optional satellite radio and navigation.

Audio System:

Standard 6-speaker or optional premium audio system.

Cruise Control:

Standard electronic cruise control.

Instrument Cluster:

Analog gauges with integrated digital multi-function display, including boost gauge and gear position indicator.

Aux Input:

Available 3.5mm auxiliary audio input jack.

🔧 Maintenance

Oil Change Interval:

Every 3,750 miles or 6 months (severe driving conditions), or 7,500 miles / 12 months (normal conditions), using full synthetic 5W-30 or 10W-30.

Engine Air Filter:

Inspect every 15,000 miles, replace as needed.

Cabin Air Filter:

Inspect/replace every 15,000 miles or annually.

Spark Plugs:

Replace every 60,000 miles (iridium type).

Timing Belt:

Replace every 105,000 miles or 84 months (critical item, includes tensioner and idlers).

Brake Fluid:

Flush/replace every 30,000 miles or 3 years.

Coolant:

Replace Subaru Super Coolant (blue) every 30,000 miles or 3 years initially, then every 60,000 miles or 6 years thereafter.

Engine Oil:

SAE 5W-30 or 10W-30, API SN/SP, ILSAC GF-5/GF-6 (synthetic recommended for STI)

Coolant:

Subaru Super Coolant (Blue) or equivalent silicate-free OAT coolant.

Brake Fluid:

DOT 3 or DOT 4 brake fluid.

Power Steering Fluid:

Subaru Extra HP Power Steering Fluid or Dexron II/III ATF.

Engine Reliability:

Head gasket failures (less common on EJ257 than earlier EJ25 variants but still possible), piston ringland failure (often due to detonation/knock), oil consumption, turbocharger wear (especially if neglected).

Drivetrain Reliability:

Clutch wear, differential issues (especially with aggressive driving or high mileage), DCCD system faults.

Suspension Wear:

Strut mounts, bushings, and ball joints can wear over time, affecting alignment and handling.

Electrical Gremlins:

Corrosion on connectors, particularly in the engine bay and undercarriage; minor electrical glitches can occur with age.

📚 Vehicle History

Heritage:

Subaru, a division of Subaru Corporation (formerly Fuji Heavy Industries), has a long history in motorsport, particularly rallying, with the Impreza WRX and WRX STI being its most iconic performance models.

Third Generation Introduction:

The WRX STI received a significant redesign for the 2006 model year, moving to a new platform and offering a more refined, yet still potent, performance package. This generation also saw the introduction of the STI hatchback body style in later years, though the 2006-2007 primarily represent the sedan form factor before the major chassis change to the GR/GV generation.

Key Updates 0607:

Introduction of the new chassis, updated engine tuning, larger intercooler, and revised suspension geometry for improved handling. The DCCD system also saw refinements.

Production Period:

2006-2007 (specific generation)

Manufacturing Location:

Japan

🏆 Awards & Recognition

Car And Driver 10Best:

Impreza WRX/STI models often featured on Car and Driver's 10Best lists during this era for their performance and value.

Motorsport Achievements:

Numerous rally championships and strong showings in various motorsport disciplines, reinforcing the WRX STI's performance pedigree.