🏷️ Basic Information

Make:

Subaru

Model:

Impreza WRX STi

Year:

2006

Generation Code:

GDB (Third Generation)

Chassis Code:

GDB

👋 Introduction

Positioning:

The 2006 Impreza WRX STi represents the pinnacle of Subaru's rally-bred performance sedan for that era, offering a blend of everyday usability and track-ready capability.

Competitors:

Competed against performance variants of the Mitsubishi Lancer Evolution, Subaru Legacy GT, Ford Focus RS, and Volkswagen Golf R.

Performance Focus:

Iconic symmetrical all-wheel drive system, turbocharged Boxer engine, DCCD (Driver Controlled Center Differential), performance braking system.

Handling:

Tuned suspension for aggressive driving, responsive steering, and balanced chassis dynamics.

📋 Manual Details

Covered Regions:

Global (primary focus on North American/Japanese market specifications)

Page Count:

Approximately 2500+

Type:

Factory Service Manual / Workshop Manual

Language:

English

Format:

Digital (PDF)

📖 Manual Coverage

Engine:

2.5L EJ257 Turbocharged Boxer Engine, including maintenance, diagnosis, disassembly, and assembly procedures.

Transmission:

6-speed manual transmission (TY856WB2CA), including clutch system, driveline, differentials (front, center, rear).

Brakes:

Front Brembo 4-piston calipers, rear 2-piston calipers, ABS, EBD, and brake system diagnostics.

Suspension:

Front MacPherson struts, rear double wishbone, adjustable ride height and damping systems, alignment specifications.

Electrical:

Full wiring diagrams, ECU pinouts, sensor testing, charging system, starting system, lighting, comfort systems, power accessories.

Chassis Body:

Body and frame structure, doors, hood, trunk, glass, exterior trim, interior trim, HVAC, SRS (airbag) system.

Fuel System:

Fuel tank, fuel pump, injectors, fuel pressure regulation, emissions control system (EVAP).

Cooling System:

Radiator, thermostat, water pump, cooling fan operation, coolant specifications.

Exhaust System:

Exhaust manifold, catalytic converter, mufflers, performance considerations.

Maintenance:

Routine service checks, oil and filter changes, spark plug replacement, fluid checks and top-offs, belt inspections and replacement.

Troubleshooting:

Diagnostic trouble codes (DTCs), symptom-based diagnostics for engine, transmission, electrical, and HVAC systems.

Repair:

Engine component replacement (pistons, rods, bearings, valves), turbocharger overhaul, transmission rebuilds, brake caliper replacement, suspension component replacement.

Diagnostics:

OBD-II diagnostic procedures, live data analysis, specialized Subaru diagnostic tools (e.g., Subaru Select Monitor).

Timing:

Timing belt replacement (on earlier EJ20/EJ25, though EJ257 often uses a timing chain/belt hybrid system depending on variant, manual clarifies specific setup), camshaft and crankshaft timing.

Calibration:

ECU reprogramming, idle air control valve (IACV) learning, throttle position sensor (TPS) calibration.

Depth:

Comprehensive from basic maintenance to full engine and transmission overhaul, including detailed torque specifications and assembly sequences.

📊 Manual Specifications

PDF Quality:

High-resolution, searchable PDF with clear text and legible diagrams.

Searchability:

Full text search enabled for quick access to specific topics and procedures.

Printable:

Printable pages for workshop use.

Binding:

N/A (Digital Format)

Paper:

N/A (Digital Format)

⚙️ Engine Specifications

Engine Code:

EJ257

Engine Type:

2.5L (2457cc) DOHC 16-valve turbocharged horizontally-opposed (Boxer) 4-cylinder engine.

Horsepower:

300 hp @ 6000 rpm (SAE Net)

Torque:

290 lb-ft @ 4000 rpm (SAE Net)

Injection Type:

Multi-point fuel injection (MPI) with Denso side-feed fuel injectors.

Turbocharger:

IHI VF37 twin-scroll turbocharger.

Intercooler:

Top-mounted air-to-air intercooler.

Fuel Requirement:

Premium Unleaded Gasoline (91 octane or higher recommended).

🔧 Transmission

Transmission Type:

6-speed manual transmission

Transmission Code:

TY856WB2CA

Dccd:

Driver Controlled Center Differential (DCCD) with auto/manual modes for torque distribution adjustment.

All Wheel Drive:

Symmetrical All-Wheel Drive system with viscous coupling center differential and Torsen front differential, rear limited-slip differential (LSD).

📐 Dimensions

Length:

4405 mm (173.4 in)

Width:

1795 mm (70.7 in)

Height:

1440 mm (56.7 in)

Wheelbase:

2625 mm (103.3 in)

Curb Weight:

1470 kg (3240 lbs)

🛡️ Safety Features

NHTSA Front Impact:

5-Star

NHTSA Side Impact:

5-Star

ABS:

Anti-lock Braking System (ABS) with Electronic Brake-force Distribution (EBD).

Traction Control:

Vehicle Dynamics Control (VDC) - standard on some markets/trims, often optional or tied to AWD system.

Airbags:

Driver and front passenger airbags, front side-impact airbags.

Seatbelts:

3-point front and rear seatbelts with pretensioners and load limiters.

💡 Technology Features

Head Unit:

Factory AM/FM/CD audio system. Options for auxiliary input or upgraded head units common.

Gauges:

Driver-focused gauge cluster with tachometer, speedometer, boost gauge, and multi-function display.

AWD Control:

Advanced Symmetrical AWD with Driver Controlled Center Differential (DCCD) for optimized traction and handling in various conditions.

ABS Ebd:

Standard ABS and EBD for enhanced braking control.

🔧 Maintenance

Oil Change:

Every 3,000-5,000 miles or 6 months, whichever comes first, especially under hard driving conditions. Synthetic oil recommended.

Spark Plugs:

Typically 30,000 miles for Iridium spark plugs (check manual for specific PN).

Timing Belt:

For EJ257 engines that utilize a belt, typically 105,000 miles or 7 years. Critical item; manual provides exact procedure and tensioning specs.

Brake Fluid:

Every 2 years or 30,000 miles.

Engine Oil:

SAE 5W-30 Synthetic (API SN/SP or ILSAC GF-6) - Check manual for exact PN and capacity (approx. 5.0 quarts).

Transmission Fluid:

Subaru Genuine Manual Transmission Fluid (API GL-5) or equivalent. Capacity approx. 2.7 liters.

Differential Fluid Front:

Subaru Genuine Differential Gear Oil (API GL-5) or equivalent. Capacity approx. 1.0 liter.

Differential Fluid Rear:

Subaru Genuine Differential Gear Oil (API GL-5) or equivalent. Capacity approx. 1.2 liters.

Coolant:

Subaru Super Coolant (Blue) or equivalent. Capacity approx. 7.7 liters.

Piston Slap:

Some EJ257 engines may exhibit piston slap, particularly on cold starts. Manual provides diagnostics for this.

Ring Land Failure:

Can occur due to detonation/pre-ignition. Proper fuel, tuning, and maintenance are crucial. Manual details engine build and component tolerances.

Clutch Wear:

High-performance nature can lead to accelerated clutch wear with aggressive driving. Manual outlines clutch inspection and replacement.

Turbocharger Failure:

Can be caused by oil starvation or debris. Manual provides maintenance procedures and troubleshooting for the IHI VF37 turbo.

📚 Vehicle History

Rally Roots:

Subaru's deep roots in the World Rally Championship (WRC) heavily influenced the development and performance of the Impreza WRX and WRX STi models.

Gc8 To Gdb:

The 2006 model year marks a transition to the second generation of the GD chassis Impreza, often referred to as the 'blobeye' or 'hawkeye' depending on minor styling updates throughout its lifecycle. This generation brought significant chassis improvements and engine upgrades.

Production Location:

Gunma Plant, Japan.

🏆 Awards & Recognition

Performance Acclaim:

Consistently praised by automotive journalists for its exhilarating performance, rally-inspired handling, and all-weather capability.

Sport Compact Status:

Considered a benchmark in the sport compact segment during its production run.