🏷️ Basic Information

Make:

Subaru

Model:

Impreza WRX STI

Year:

2015

Chassis Code:

VAB

Generation Code:

GVA (WRX STI specific generation within the third generation Impreza)

👋 Introduction

Positioning:

High-performance compact sedan/hatchback, rallying heritage, enthusiast-focused.

Competitors:

Mitsubishi Lancer Evolution (discontinued in this generation), Ford Focus RS, Volkswagen Golf R, Honda Civic Type R.

Performance Focus:

Symmetrical All-Wheel Drive, turbocharged boxer engine, sport-tuned suspension, high-performance braking system.

Rally Heritage:

Direct lineage from World Rally Championship (WRC) cars, emphasizing driver engagement and all-weather capability.

📋 Manual Details

Region Coverage:

Global (primarily North America and European markets, applicable to all WRX STI variants for the model year)

Page Count Estimated:

Over 2000 pages (typical for a full factory service manual)

Manual Type:

Factory Service Manual / Workshop Manual

Language:

English

Format:

Digital (PDF)

📖 Manual Coverage

Engine Mechanical:

Engine assembly, disassembly, overhaul, timing, lubrication, cooling, fuel delivery, ignition, exhaust, turbocharger systems.

Engine Electrical:

ECU diagnosis, sensor circuits, actuators, wiring diagrams, starter, alternator, battery.

Transmission:

Manual transmission (TY76) repair, clutch system, differential service (front, rear, center viscous coupling).

Drivetrain:

Driveshafts, CV joints, wheel bearings, AWD system components.

Suspension:

Front and rear suspension geometry, shock absorbers, springs, control arms, anti-roll bars, alignment specifications.

Steering:

Power steering system, steering rack, column, tie rods, alignment.

Brakes:

Front and rear brake systems (Brembo calipers standard), ABS, EBD, brake fluid specifications, bleeding procedures, rotor/pad replacement.

Electrical Body:

Lighting, power windows, door locks, wipers, horn, interior/exterior trim removal, body panel repair.

Climate Control:

HVAC system, refrigerant handling, heater core, A/C compressor, blower motor.

Safety Systems:

Airbag system, seatbelt pretensioners, SRS wiring.

Diagnostic Troubleshooting:

Step-by-step diagnostic procedures for common fault codes and symptoms, guided troubleshooting trees.

Routine Maintenance:

Oil changes, filter replacements, fluid checks and top-offs, spark plug replacement, belt inspections.

Component Replacement:

Detailed instructions for replacing major and minor components across all systems.

Rebuild Procedures:

Engine and transmission rebuild procedures, including torque specifications and clearances.

Wiring Diagrams:

Comprehensive electrical system wiring diagrams with component identification and circuit tracing.

Specification Data:

Torque specifications, clearances, fluid capacities, electrical resistance values, and other critical data.

Depth:

Comprehensive (covers all aspects from routine maintenance to complete engine rebuilds and advanced diagnostics).

📊 Manual Specifications

Digital Format:

PDF (Searchable text, bookmark navigation, printable pages).

Print Quality:

High-resolution (suitable for printing individual pages or the entire manual).

Binding Type:

N/A (Digital Format)

Paper Type:

N/A (Digital Format)

⚙️ Engine Specifications

Engine Code:

EJ257

Engine Type:

2.5L Turbocharged Boxer-4 (EJ257)

Bore X Stroke:

99.5 mm x 79.0 mm

Compression Ratio:

8.4:1

Engine Management:

Multi-point Fuel Injection (MPI), Electronic Throttle Control (ETC), Variable Valve Timing (VVT).

Horsepower Ps:

305 PS @ 6000 rpm

Torque Lb-Ft:

290 lb-ft @ 4000 rpm

Redline:

7100 rpm

Fuel Type:

Premium Unleaded Gasoline (91 AKI or higher recommended)

Fuel Delivery:

Sequential electronic fuel injection.

Turbocharger:

Twin-scroll turbocharger with intercooler.

🔧 Transmission

Type:

6-speed Manual Transmission (TY76)

Type:

N/A for WRX STI 2015 (Manual only)

All Wheel Drive:

Symmetrical All-Wheel Drive (SAWD) with Driver Controlled Center Differential (DCCD).

Differential Type:

Helical limited-slip front differential, Viscous coupling all-wheel drive center differential, Torsen limited-slip rear differential.

Manual Transmission Fluid:

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

Rear Differential Fluid:

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

📐 Dimensions

Length:

4415 mm (173.8 in)

Width:

1795 mm (70.7 in)

Height:

1475 mm (58.1 in)

Wheelbase:

2650 mm (104.3 in)

Ground Clearance:

135 mm (5.3 in)

Curb Weight:

Approximately 1505 kg (3318 lbs)

Gross Vehicle Weight Rating:

N/A (Typically not specified for performance models in manuals)

Towing Capacity:

Not Recommended

Trunk Volume Sedan:

340 L (12.0 cu ft) (approximate)

Trunk Volume Hatchback:

Not Applicable (This generation WRX STI was Sedan only)

🛡️ Safety Features

IIHS Top Safety Pick:

Top Safety Pick+ (for certain configurations in the US market)

NHTSA Overall Rating:

5-Star (Overall safety rating in US market)

Traction Control:

Vehicle Dynamics Control (VDC) with Sport Mode.

Electronic Stability Control:

Standard

Brake Assist:

Yes (BA)

Anti Lock Brakes:

Yes (ABS) with Electronic Brake-force Distribution (EBD).

Airbags:

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

Seatbelts:

3-point seatbelts with pretensioners and force limiters.

Child Seat Anchors:

LATCH (Lower Anchors and Tethers for CHildren) system.

💡 Technology Features

Head Unit:

Standard 6.2-inch touchscreen infotainment system with Subaru Starlink.

Audio System:

Available Harman Kardon premium audio system.

Connectivity:

Bluetooth hands-free connectivity, USB port, auxiliary audio input.

Key Features:

Standard backup camera. Optional EyeSight driver assistance suite was not widely available on the 2015 STI.

Si Drive:

Subaru Intelligent Drive system allowing driver selection of Intelligent, Sport, and Sport Sharp modes, altering throttle response, VDC logic, and DCCD settings.

Dccd:

Driver Controlled Center Differential allows manual adjustment of the front-to-rear torque split.

🔧 Maintenance

Oil Change Interval:

Every 3,750 miles or 6 months, whichever comes first (under severe driving conditions, which often applies to STI usage).

Air Filter Replacement:

Every 15,000 miles or 12 months.

Cabin Air Filter Replacement:

Every 7,500 miles or 6 months.

Spark Plug Replacement:

Every 30,000 miles.

Coolant Replacement:

Initial: 45,000 miles/48 months. Subsequent: 30,000 miles/24 months.

Brake Fluid Change:

Every 30,000 miles or 24 months.

Engine Oil Capacity:

5.1 US quarts (4.8 L) with filter (5W-30 Synthetic Recommended)

Coolant Type:

Subaru Super Coolant (Blue) or equivalent P-OAT antifreeze.

Brake Fluid Type:

DOT 3 or DOT 4.

Piston Ring Land Cracks:

Historically, EJ25 engines can be susceptible to piston ring land cracks, particularly with aggressive tuning or sustained high boost. The 2015 STI EJ257 is generally more robust, but vigilance is advised.

Clutch Wear:

High-performance clutch can experience accelerated wear with aggressive driving or frequent clutch dumps.

Turbocharger Wear:

While robust, turbochargers are high-stress components and can fail over time, especially if maintenance is neglected or if subjected to extreme conditions.

Water Pump Leaks:

Water pump seals can degrade over time, leading to coolant leaks.

📚 Vehicle History

Rally Focus:

Subaru's long and successful history in the World Rally Championship (WRC), winning multiple championships.

Generations:

The 2015 model represents the second generation of the WRX and WRX STI to be based on the Impreza platform, but with a distinct chassis and bodywork, marking a significant separation from the standard Impreza.

Subaru Performance Division:

STI (Subaru Tecnica International) is Subaru's performance and motorsport division, responsible for the development of the WRX STI.

Manufacturing Location:

Ota City, Gunma Prefecture, Japan

🏆 Awards & Recognition

Performance Car Awards:

Consistently recognized by automotive publications for its performance, handling, and all-wheel-drive capabilities.

Track Day Staple:

Popular choice for track days and autocross events due to its chassis dynamics and AWD system.

Homologation:

STI models are often developed with motorsport homologation in mind, influencing their mechanical design.