🏷️ Basic Information

Make:

Subaru

Model:

Impreza WRX STI

Year:

2015

Product Name:

Subaru Impreza WRX STI Complete Workshop Service Repair Manual 2015

👋 Introduction

Vehicle Segment:

Performance compact sedan/hatchback.

Target Audience:

Enthusiasts, performance drivers, DIY mechanics, professional technicians seeking in-depth repair information.

Competitors:

Mitsubishi Lancer Evolution, Volkswagen Golf GTI, Ford Focus RS, Honda Civic Type R (though WRX STI often occupies a more rally-bred, AWD performance niche).

Performance Orientation:

The WRX STI variant is distinguished by its turbocharged boxer engine, Symmetrical All-Wheel Drive system, and performance-tuned suspension, making it a homologation special derived from rally racing heritage.

Manual Value Proposition:

This manual provides comprehensive, factory-level information crucial for maintaining and repairing the complex mechanical and electronic systems of the 2015 WRX STI, enabling owners and technicians to perform services accurately and efficiently.

📋 Manual Details

Manual Type:

Workshop Service Repair Manual

Language:

English

Format:

Downloadable PDF

📖 Manual Coverage

Engine Mechanical:

Engine assembly, disassembly, cylinder head, crankshaft, connecting rods, pistons, valve train, timing system, lubrication system, cooling system, fuel system, intake system, exhaust system.

Engine Electrical:

Engine control module (ECM), ignition system, fuel injection system, sensors, actuators, wiring diagrams, diagnostic trouble codes (DTCs).

Transmission Manual:

Clutch system, transmission assembly, disassembly, gear sets, synchronizers, shift mechanisms, lubrication, maintenance, troubleshooting.

Transmission Automatic:

Not applicable for WRX STI models which typically feature a manual transmission only. If an automatic variant exists, coverage would include torque converter, planetary gear sets, hydraulic control system, electronic controls, fluid maintenance, and diagnostics.

Drivetrain:

All-Wheel Drive (AWD) system, center differential, front differential, rear differential, driveshafts, CV joints, wheel bearings.

Suspension:

Front suspension (MacPherson struts), rear suspension (double wishbone), springs, shock absorbers, control arms, anti-roll bars, bushings, alignment specifications.

Steering:

Power steering system (hydraulic or electric), steering column, steering rack, tie rod ends, steering angle sensor.

Brakes:

Front and rear disc brakes, brake calipers, brake pads, brake rotors, brake lines, master cylinder, brake booster, ABS system, EBD system, parking brake.

Electrical System:

Battery, alternator, starter motor, lighting system (headlights, taillights, interior), fuses, relays, wiring harnesses, power windows, power locks, mirrors, horn, wipers.

Body And Frame:

Body panels, chassis components, doors, hood, trunk, bumpers, glass, seals, sound deadening, rust prevention, corrosion control.

Interior:

Seats, dashboard, center console, upholstery, trim panels, airbags, seatbelts, HVAC system controls, audio system, instrument cluster.

HVAC System:

Air conditioning (AC) system, heater core, blower motor, climate control panel, refrigerant handling, diagnostic procedures.

Safety Systems:

Airbag system, SRS module, seatbelt pre-tensioners, ABS, traction control, stability control.

Routine Maintenance:

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

Troubleshooting:

Diagnostic procedures for common and uncommon issues, symptom-based troubleshooting guides, DTC interpretation and resolution.

Repair And Rebuild:

Step-by-step instructions for major component repairs and rebuilds, including engine, transmission, differentials, suspension, steering, brakes, and more.

Component Replacement:

Detailed guides for replacing individual components such as starters, alternators, water pumps, fuel pumps, radiators, AC compressors, turbochargers, clutches, and more.

Electrical Diagnostics:

Testing circuits, component testing, wiring harness inspection, troubleshooting electrical faults, using diagnostic tools.

Torque Specifications:

Precise torque values for all critical fasteners to ensure proper assembly and prevent component damage.

Wiring Diagrams:

Comprehensive electrical wiring schematics for all vehicle systems, aiding in diagnostics and repairs.

Depth Of Coverage:

Complete, covering everything from basic fluid checks and filter replacements to full engine and transmission rebuilds. Includes advanced diagnostic procedures and detailed component specifications.

📊 Manual Specifications

File Type:

PDF

Searchability:

Searchable text for quick information retrieval.

Printability:

Printable pages for easy reference during service.

Page Count Estimate:

~2000+ pages (typical for comprehensive workshop manuals of this era and vehicle complexity).

Quality:

High-resolution scans or original manufacturer digital files.

Binding Type:

N/A (Downloadable format)

Paper Type:

N/A (Digital format)

⚙️ Engine Specifications

Engine Code:

EJ257

Engine Type:

2.5L Boxer-4 Turbocharged DOHC 16-valve

Bore X Stroke:

99.5 mm x 79.0 mm

Displacement:

2457 cc (2.5 Liters)

Horsepower:

305 hp @ 6000 rpm

Torque:

290 lb-ft @ 4000 rpm

Fuel Delivery:

Multi-point fuel injection (MPI) with Subaru's electronic throttle control.

Fuel Type:

Premium Unleaded Gasoline (91 octane or higher recommended)

Turbocharger:

IHI VF48 Twin-Scroll Turbocharger

Intercooler:

Air-to-air top-mount intercooler.

Compression Ratio:

8.2:1

🔧 Transmission

Transmission Type:

6-speed Manual Transmission

Transmission Code:

TY89

Transmission Type:

Not Applicable for 2015 WRX STI (Manual only)

Drivetrain System:

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

Dccd Modes:

Automatic, Manual (six settings), and Lock modes for optimal torque distribution in various conditions.

Clutch Type:

Hydraulically actuated, multi-plate clutch.

📐 Dimensions

Length:

4,465 mm (175.8 in)

Width:

1,795 mm (70.7 in)

Height:

1,475 mm (58.1 in)

Wheelbase:

2,650 mm (104.3 in)

Ground Clearance:

135 mm (5.3 in)

Curb Weight:

~1,510 kg (3,329 lbs) - varies slightly by body style

Gross Vehicle Weight Rating:

Approx. 2,000 kg (4,409 lbs)

Towing Capacity:

Not recommended/specified by Subaru for WRX STI models.

🛡️ Safety Features

NHTSA Ratings:

Generally good, with specific ratings varying by year and test protocols. Often receives 4 or 5 stars in frontal and side crash tests.

IIHS Ratings:

Often achieves 'Good' ratings in key crashworthiness categories.

ABS:

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

Traction Control:

Traction Control System (TCS).

Stability Control:

Vehicle Dynamics Control (VDC) with Sport Mode.

Airbags:

Multi-stage front airbags, front side-impact airbags, side curtain airbags.

Seatbelts:

3-point ELR front and rear seatbelts with pre-tensioners and force limiters, front seatbelt reminder.

Chassis Design:

Ring-shaped reinforcement frame, front and rear crumple zones, energy-absorbing steering column.

💡 Technology Features

Head Unit:

Standard touchscreen infotainment system with AM/FM/CD/MP3 player, Bluetooth connectivity, USB ports, and auxiliary input.

Navigation:

Optional navigation system available.

Audio System:

Standard 6-speaker audio system, optional Harman Kardon premium audio system.

Performance Tools:

SI-DRIVE (Subaru Intelligent Drive) system allowing driver to select between Intelligent, Sport, and Sport Sharp modes for engine and transmission response.

Instrument Cluster:

Performance-oriented instrument cluster with a multi-information display showing boost pressure, G-force meter, and other performance metrics.

Bluetooth:

Bluetooth hands-free calling and audio streaming.

Usb Aux:

USB and auxiliary input jacks for external media devices.

🔧 Maintenance

Oil Change Interval:

Every 3,750 miles or 6 months, whichever comes first (severe driving conditions recommended for STI).

Air Filter Replacement:

Every 15,000 miles or 12 months.

Cabin Filter Replacement:

Every 15,000 miles or 12 months.

Spark Plug Replacement:

Iridium spark plugs typically last 60,000 - 105,000 miles, check specific recommendations.

Brake Fluid Flush:

Every 30,000 miles or 24 months.

Coolant Flush:

First at 30,000 miles or 24 months, then every 15,000 miles or 12 months thereafter.

Engine Oil Type:

SAE 0W-20, API SN, ILSAC GF-5 (for normal use) or SAE 5W-30, API SN, ILSAC GF-5 (for spirited/track use), synthetic recommended. Consult manual for specific STI requirements.

Engine Oil Capacity:

5.8 US quarts (5.5 Liters) with filter change.

Coolant Type:

Subaru Super Coolant (Blue) or equivalent silicate and amine-free antifreeze (50/50 mix with distilled water).

Transmission Fluid Type:

Genuine Subaru Extra-S Gear Oil (75W-90 GL-5) or equivalent for manual transmission. Refer to manual for specific AWD fluid requirements (e.g., differential fluids).

Brake Fluid Type:

DOT 3 or DOT 4.

Head Gasket Leaks:

While less common on EJ257 than earlier EJ engines, head gasket integrity is crucial. Monitor for coolant loss or exhaust gases in coolant.

Ringland Failure:

Can occur with aggressive tuning or high-performance driving if not properly maintained and managed. Monitor for loss of compression or misfires.

Turbocharger Wear:

Proper warm-up and cool-down procedures are essential. Check for oil leaks or bearing play.

Clutch Wear:

Performance clutches can wear faster under aggressive use. Listen for noise or feel for slipping.

📚 Vehicle History

Subaru Motorsport:

Subaru's deep roots in World Rally Championship (WRC) racing directly influenced the development and DNA of the WRX STI, emphasizing AWD performance and driver engagement.

Impreza Generations:

The 2015 model represents the start of the fourth generation (GV/GR chassis) for the WRX STI, though it shares a platform with the standard Impreza. It introduced a more mature design and significant chassis revisions.

Sti Development:

STI (Subaru Tecnica International) is Subaru's performance division, responsible for tuning and enhancing Subaru vehicles for motorsport and road-going performance.

Manufacturing Location:

Gunma Plant, Japan

Production Years:

The WRX STI nameplate has been in production since the 1990s, with the 2015 model being a significant update.

🏆 Awards & Recognition

Motortrend Awards:

Subaru WRX STI models have often been lauded for their performance capabilities and value within their segment.

Car And Driver Features:

Frequently featured in performance-oriented comparisons and 'best of' lists for its handling and AWD prowess.

Enthusiast Community:

Highly regarded within the automotive enthusiast community for its rally heritage and capability.