🏷️ Basic Information

Make:

Subaru

Model:

Impreza WRX STI

Year:

2012

Chassis Code:

GV/GR

👋 Introduction

Vehicle Segment:

Performance Compact Sedan/Hatchback (rally-bred homologation special)

Target Audience:

Enthusiasts, performance drivers, rally fans, DIY mechanics.

Key Competitors:

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

Drivetrain:

Symmetrical All-Wheel Drive (AWD) with Driver's Control Centre Differential (DCCD) and Active Torque Distribution.

Engine Performance:

High-output turbocharged Boxer engine with strong low-end and mid-range torque.

Handling:

Renowned for exceptional grip, steering response, and chassis dynamics.

Braking:

Powerful Brembo brakes providing superior stopping power and fade resistance.

Interior Focus:

Driver-centric cockpit with performance-oriented seating and controls.

📋 Manual Details

Manual Type:

Workshop Service Repair Manual

Language:

English

Format:

PDF

Documentation Scope:

Repair and Overhaul Procedures

Assumed Technician Knowledge:

Fully conversant with general automobile practices

📖 Manual Coverage

Engine:

EJ257 2.5L Turbocharged Boxer Engine, including assembly, disassembly, diagnostics, tuning, and emissions control systems.

Transmission:

6-speed Manual Transmission (TY856), including clutch, drivetrain components (differentials, axles), and gearbox overhaul.

Suspension:

Performance-tuned suspension system (STI specific), including struts, springs, anti-roll bars, bushings, and alignment procedures.

Brakes:

Brembo performance braking system, including front and rear calipers, rotors, pads, fluid flush, and ABS system diagnostics.

Electrical:

Comprehensive electrical schematics, wiring diagrams, battery, alternator, starter, ignition system, lighting, audio system, and diagnostic port (OBD-II).

Body And Chassis:

Body panel repair, structural integrity, door mechanisms, glass replacement, and underbody protection.

Cooling System:

Radiator, thermostat, water pump, coolant specifications, and leak detection procedures.

Fuel System:

Fuel injectors, fuel pump, fuel lines, fuel pressure regulation, and emissions control (EVAP).

Exhaust System:

Catalytic converter, mufflers, exhaust manifold, and gasket replacement.

HVAC:

Air conditioning system, heater core, climate control unit, and refrigerant handling.

Maintenance:

Oil changes, filter replacements (oil, air, cabin), spark plug replacement, fluid checks and top-offs, belt inspection.

Troubleshooting:

Diagnostic charts, symptom-based troubleshooting for engine, transmission, electrical, and chassis issues.

Repair:

Engine rebuild, transmission overhaul, brake caliper replacement, suspension component replacement, electrical component repair.

Overhaul:

Complete disassembly and reassembly of major components like the engine and transmission.

Diagnostics:

Advanced diagnostic procedures using scan tools, testing of sensors, actuators, and control modules.

Alignment:

Wheel alignment specifications and procedures for performance handling.

Torque Specifications:

Detailed torque values for all critical fasteners across all systems.

Depth Level:

Comprehensive, covering routine maintenance to complete engine and transmission rebuilds.

Diagnostic Capability:

Advanced diagnostic fault code interpretation and system-specific testing.

Component Rebuild:

Detailed instructions for rebuilding major mechanical and electrical assemblies.

Schematics Detail:

High-resolution electrical wiring diagrams with component identification.

📊 Manual Specifications

File Type:

PDF

Searchability:

Text-searchable PDF for easy navigation and information retrieval.

Printability:

Printable pages for workshop use.

Resolution:

High-resolution graphics and diagrams.

Binding Type Physical:

Not applicable (PDF format)

Paper Type Physical:

Not applicable (PDF format)

⚙️ Engine Specifications

Engine Code:

EJ257

Engine Type:

2.5L DOHC 16-valve turbocharged horizontally-opposed (Boxer) 4-cylinder

Bore X Stroke:

99.5 mm x 79.0 mm

Compression Ratio:

8.4:1

Horsepower:

305 HP @ 6000 RPM

Torque:

290 lb-ft @ 4000 RPM

Redline:

7000 RPM

Fuel Delivery:

Multi-point fuel injection (MPI) with high-flow injectors

Fuel Type:

Premium Unleaded Gasoline (91 octane or higher recommended)

Turbocharger:

Single-scroll IHI VF48 turbocharger with intercooler

🔧 Transmission

Transmission Type:

6-speed Manual Transmission (TY856)

Gear Ratios:

1st: 3.636, 2nd: 2.244, 3rd: 1.615, 4th: 1.243, 5th: 0.972, 6th: 0.756, Reverse: 3.545

Optional Transmission:

N/A for WRX STI model year 2012

Drivetrain Layout:

Symmetrical All-Wheel Drive (AWD)

Center Differential:

Driver's Control Centre Differential (DCCD) with Auto/Manual modes

Rear Differential:

Mechanical Limited-Slip Differential (LSD)

Front Differential:

Viscous Coupling Limited-Slip Differential (VLSD)

📐 Dimensions

Length:

179.5 inches (4560 mm)

Width:

70.7 inches (1796 mm)

Height:

57.7 inches (1466 mm)

Wheelbase:

103.2 inches (2620 mm)

Track Width Front:

60.6 inches (1540 mm)

Track Width Rear:

60.4 inches (1535 mm)

Ground Clearance:

5.0 inches (127 mm)

Curb Weight:

Approx. 3,417 lbs (1550 kg) for sedan, 3,439 lbs (1560 kg) for hatchback

Gross Vehicle Weight Rating:

4,630 lbs (2100 kg)

Towing Capacity:

Not Recommended

Trunk Volume Sedan:

11.3 cubic feet (320 Liters)

Cargo Volume Hatchback:

20.0 cubic feet (566 Liters) with rear seats up

Cargo Volume Hatchback Seats Folded:

44.5 cubic feet (1260 Liters)

🛡️ Safety Features

NHTSA Overall Rating:

4 Stars (for 2012 model)

IIHS Top Safety Pick:

Yes (for 2012 model)

ABS:

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

Traction Control:

Vehicle Dynamics Control (VDC) with Traction Control System (TCS)

AWD:

Symmetrical All-Wheel Drive (AWD) for enhanced traction and stability

Brake Assist:

Brake Assist System (BAS)

Airbags:

Dual-stage front airbags, front side-impact airbags, side-curtain airbags (front and rear).

Seatbelts:

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

Child Anchors:

LATCH (Lower Anchors and Tethers for Children) system

Body Structure:

Advanced front and side impact protection structure

💡 Technology Features

Head Unit:

Standard Subaru AM/FM/CD/MP3 stereo with auxiliary input. Optional Rockford Fosgate premium audio system available.

Display:

Multi-function display in the instrument cluster (fuel economy, AWD system status).

Cruise Control:

Standard electronic cruise control.

Keyless Entry Start:

Keyless entry with push-button ignition available on certain trims.

Bluetooth:

Bluetooth hands-free calling and audio streaming available on select trims/packages.

Usb Port:

USB port for audio device connectivity available on select trims/packages.

🔧 Maintenance

Oil Change Interval:

Every 3,750 miles or 3.75 months (under severe driving conditions) or 7,500 miles or 7.5 months (under normal driving conditions).

Air Filter Replacement:

Every 15,000 miles or 15 months.

Cabin Filter Replacement:

Every 7,500 miles or 7.5 months.

Spark Plug Replacement:

Every 30,000 miles (for iridium-tipped plugs).

Coolant Flush:

Every 30,000 miles or 30 months.

Brake Fluid Flush:

Every 15,000 miles or 15 months (recommended for performance driving).

Transmission Fluid Change Manual:

Every 30,000 miles or 30 months.

Differential Fluid Change Front Rear:

Every 30,000 miles or 30 months.

Engine Oil Type:

SAE 5W-30 Synthetic (API SG, SH, SJ, SL, SM, SN, or ILSAC GF-2, GF-3, GF-4, GF-5)

Engine Oil Capacity:

5.5 US quarts (5.2 Liters) with filter change.

Coolant Type:

Subaru Super Coolant (Blue) or equivalent silicate-free, long-life antifreeze.

Transmission Fluid Type Manual:

API GL-5, SAE 75W-90 gear oil (check manual for specific recommendations, often with limited-slip additive for rear diff).

Brake Fluid Type:

DOT 3 or DOT 4 High-Temperature Brake Fluid.

Engine Knock:

Detonation or 'knock' due to improper fuel, carbon buildup, or faulty knock sensor. Requires careful diagnosis and potential ECU reflash.

Clutch Wear:

Can wear prematurely with aggressive driving or frequent launching. Clutch chatter can also occur.

Turbocharger Wear:

Bearing wear or seal failure can occur, especially if oil changes are neglected or if the turbo is subjected to extreme heat cycling without proper cool-down.

Suspension Bushings:

Front and rear suspension bushings can degrade over time, leading to clunks or imprecise handling.

Oil Consumption:

Some EJ25 engines can exhibit higher than normal oil consumption, particularly at higher mileage. Piston ring issues are a potential cause.

📚 Vehicle History

Brand Legacy:

Subaru is renowned for its Symmetrical All-Wheel Drive system and horizontally-opposed Boxer engines, stemming from its rallying heritage.

Wrx Sti Lineage:

The WRX STI is Subaru's flagship performance model, directly derived from its World Rally Championship (WRC) competition cars. The 2012 model represents the third generation (GE/GH/GR/GV) of the Impreza, with the sedan and hatchback body styles for the STI.

Third Generation Debut:

The third generation Impreza, including the STI, debuted for the 2008 model year. The 2012 model year saw a significant facelift with revised styling.

Production Plant:

Gunma Manufacturing Plant, Ota, Gunma, Japan

Production Years Global:

2008-2014 (Third Generation Impreza)

🏆 Awards & Recognition

Performance Acclaim:

Consistently praised by automotive press for its dynamic abilities, rally-inspired performance, and AWD grip.

All Wheel Drive Technology:

Subaru's Symmetrical AWD and DCCD are frequently highlighted as best-in-class for performance and all-weather capability.

Resale Value:

Generally holds strong resale value due to its enthusiast following and performance credentials.

Emissions Compliance:

Meets EPA and CARB emissions standards for its model year.