🏷️ Basic Information

Make:

Subaru

Model:

Impreza WRX STI

Year:

2012

Chassis Code:

GR/GV

Platform:

Subaru Global Platform (predecessor)

👋 Introduction

Segment:

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

Target Audience:

Enthusiast drivers, tuners, motorsport participants, and owners seeking in-depth knowledge for DIY maintenance and repair.

Competitors 2012:

Mitsubishi Lancer Evolution, Volkswagen GTI, Ford Focus ST, Mazdaspeed3.

Performance Focus:

Iconic turbocharged boxer engine, symmetrical all-wheel drive, performance-tuned suspension, and driver-focused cockpit.

Value Proposition:

Provides factory-level diagnostic and repair data, essential for maintaining and optimizing the performance of a specialized vehicle like the WRX STI. Offers significant cost savings over dealership-level repairs.

Format Advantage:

PDF format allows for quick searching, easy access across devices, and printing of specific procedures as needed, unlike cumbersome physical manuals.

📋 Manual Details

Main Coverage:

Complete service, repair, and diagnostic information for the 2012 Subaru Impreza WRX STI.

Specific Areas:

Engine, Drivetrain, Suspension, Steering, Brakes, Electrical System, HVAC, Body, Chassis, Diagnostics, Maintenance.

Estimated Page Count:

Over 3000 pages (typical for a comprehensive service manual)

Type:

Factory Service Manual / Workshop Manual

Language:

English

Format:

PDF Download

📖 Manual Coverage

Powertrain:

Engine mechanical, lubrication system, cooling system, fuel system, ignition system, emissions control, turbocharger system, exhaust system, transmission (manual and automatic), clutch, all-wheel-drive system, differentials.

Chassis:

Front and rear suspension, steering system (power steering), brake system (including ABS, EBD, VDC), wheel bearings, axles.

Electrical:

Battery, charging system, starting system, lighting system, wipers and washers, horn, power windows, door locks, mirrors, instrument cluster, audio system, navigation system, SRS (airbag) system, body control module (BCM), engine control module (ECM), transmission control module (TCM).

Body And Interior:

Body panels, doors, hood, trunk lid, windows, seats, interior trim, safety belts, exterior trim, bumpers.

HVAC:

Air conditioning system, heating system, ventilation, climate control.

Maintenance:

Scheduled maintenance tasks, fluid changes (oil, coolant, brake fluid, transmission fluid, differential fluid), filter replacements, spark plug replacement, belt inspections/replacements.

Repair And Overhaul:

Engine repair (e.g., head gasket, piston/ring replacement), transmission overhaul, clutch replacement, brake pad/rotor replacement, suspension component replacement, power steering pump replacement, turbocharger removal/installation, exhaust system repair.

Diagnostics And Troubleshooting:

Troubleshooting guides based on symptoms, diagnostic trouble codes (DTCs), wiring diagrams, component testing procedures, scan tool usage.

Specifications And Tolerances:

Detailed torque specifications, clearances, measurements, and tolerances for all components.

Depth:

Comprehensive; covers basic maintenance to complete engine and transmission rebuilds, including advanced electrical diagnostics and structural repairs. Includes factory-level diagnostic procedures and specifications.

📊 Manual Specifications

File Type:

PDF

Searchability:

Likely text-searchable PDF for efficient information retrieval.

Quality:

High resolution, suitable for printing individual pages or sections.

Type:

N/A (Digital Download)

Type:

N/A (Digital Download)

⚙️ Engine Specifications

Engine Code:

EJ257

Configuration:

2.5-liter horizontally opposed (Boxer) turbocharged 4-cylinder

Bore X Stroke:

99.5 mm x 79.0 mm

Compression Ratio:

8.4:1

Valvetrain:

DOHC, 16 valves, Subaru's Variable Valve Lift & Timing (VVL-i)

Horsepower Hp:

305 hp @ 6000 rpm

Torque Lb-Ft:

290 lb-ft @ 4000 rpm

Injection Type:

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

Fuel Type:

Premium Unleaded Gasoline (91 octane or higher recommended)

Type:

Twin-scroll Mitsubishi TD04L-15G turbocharger

Intercooler:

Top-mounted, air-to-air intercooler

🔧 Transmission

Type:

6-speed Manual Transmission (TY856UR1MA)

Type:

N/A (STI exclusively featured manual transmission)

Dccd:

Driver Controlled Centre Differential (DCCD) with auto mode for variable front/rear torque split.

Differentials:

Helical Limited-Slip Front Differential, Mechanical Limited-Slip Rear Differential.

Manual Transmission Fluid:

Subaru Extra-S Gear Oil 75W-90 (or equivalent API GL-5 rated)

Manual Transmission Capacity:

Approx. 3.2 Liters (3.4 US Quarts)

📐 Dimensions

Length:

4,415 mm (173.8 in)

Width:

1,795 mm (70.7 in)

Height:

1,470 mm (57.9 in)

Wheelbase:

2,650 mm (104.3 in)

Curb Weight:

Approx. 1,505 kg (3,318 lbs) for Sedan, 1,535 kg (3,384 lbs) for Hatchback

Trunk Volume Sedan:

Approx. 0.320 m³ (11.3 cu ft)

Standard Wheel Size:

18 x 8.5 inches

Standard Tire Size:

245/40R18

Bolt Pattern:

5x114.3 mm

🛡️ Safety Features

NHTSA Overall:

5-Star (for 2012 model year in certain configurations)

IIHS Top Safety Pick:

Yes (for 2012 model year)

ABS:

Anti-lock Braking System

Ebd:

Electronic Brake-force Distribution

Vdc:

Vehicle Dynamics Control (Traction Control & Stability Control)

Airbags:

Front dual-stage airbags, front side-impact airbags, side curtain airbags.

Seatbelts:

3-point ELR seatbelts with pretensioners and force limiters.

Body Structure:

Advanced front and rear crumple zones, high-strength steel body structure.

💡 Technology Features

Head Unit:

Standard AM/FM/CD stereo with auxiliary input. Optional navigation system available.

Display:

Multi-function display in dashboard for trip computer, fuel economy, AWD system status, etc.

Cruise Control:

Standard cruise control functionality.

Keyless Entry:

Remote keyless entry system.

Usb Aux:

Auxiliary audio input jack. USB port may be present on certain trims or as an accessory.

Si Drive:

Subaru Intelligent Drive system allowing selection between Intelligent (I), Sport (S), and Sport Sharp (S#) modes, altering throttle response, engine mapping, and AWD behavior.

Data Logging:

Manual likely details how to access and interpret diagnostic data from the ECM, essential for tuning and performance analysis.

🔧 Maintenance

Oil Change Interval:

Every 3,750 miles (6,000 km) or 6 months, whichever comes first (under severe driving conditions, which is typical for STI usage). Standard interval typically 7,500 miles.

Air Filter Replacement:

Every 15,000 miles (24,000 km) or 12 months.

Spark Plug Replacement:

Every 30,000 miles (48,000 km) (Iridium type).

Timing Belt Replacement:

N/A (EJ257 uses a timing chain, but the manual will cover related component checks/maintenance).

Engine Oil Type:

SAE 5W-30 Synthetic Engine Oil (API SN or ILSAC GF-5 or higher)

Engine Oil Capacity:

Approx. 5.5 Liters (5.8 US Quarts) with filter change

Coolant Type:

Subaru Super Coolant (Blue) - Ethylene Glycol based.

Brake Fluid Type:

DOT 3 or DOT 4.

Head Gaskets:

While improved over earlier EJ engines, head gasket failures can still occur, especially with modified or aggressively driven vehicles. Manual covers inspection and replacement procedures.

Piston Ringland Failure:

Can occur due to detonation/pre-ignition, often linked to inadequate fuel quality, improper tuning, or faulty sensors. Manual provides diagnostic steps for engine knock and potential mechanical issues.

Clutch Wear:

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

Turbocharger Wear:

Can be subject to wear or failure due to heat and oil degradation. Manual covers turbo diagnostics and replacement.

Suspension Bushings:

Performance-oriented suspension can lead to wear in control arm bushings and sway bar links. Manual covers replacement of these components.

📚 Vehicle History

Motorsport Legacy:

Subaru's long and successful history in the World Rally Championship (WRC) heavily influenced the development and tuning of the WRX and STI models.

Generation Name:

Third Generation (GR/GV) Hatchback and Sedan.

Distinction From Standard Impreza:

The WRX STI diverged significantly from the standard Impreza in terms of powertrain, suspension, brakes, chassis rigidity, and exterior styling (wider fenders, hood scoop, rear spoiler).

Manufacturing Location:

Gunma Plant, Japan

Production Period:

2007-2014 (GR/GV chassis for global markets, with specific updates in 2011 and 2013).

🏆 Awards & Recognition

Performance Awards:

Consistently recognized by automotive publications for its performance capabilities and rallying heritage. Specific awards vary by publication and year.

Track Performance:

Highly regarded for its track day and autocross performance, often featured in competitive driving events.