🏷️ Basic Information

Make:

Subaru

Model:

Impreza WRX STI

Model Year:

2015

Sub Model:

WRX STI

Chassis Code:

VAB

Engine Code:

EJ257

👋 Introduction

Segment:

Performance Compact Sedan / Hatchback

Reputation:

Renowned for rally-bred performance, all-wheel-drive capability, and driver engagement.

Key Competitors:

Mitsubishi Lancer Evolution (historically), Volkswagen Golf GTI/R, Ford Focus RS (later generations), Honda Civic Type R.

Drivetrain:

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

Engine Technology:

Turbocharged Boxer Engine (EJ257) with intercooler.

Performance Tuning:

Designed for enthusiast driving and aftermarket tuning potential.

📋 Manual Details

Coverage Scope:

Comprehensive service, repair, and maintenance

Covered Systems:

Engine, Transmission, Drivetrain, Suspension, Steering, Brakes, HVAC, Electrical, Body, Chassis, Fuel, Emissions, Diagnostics

Estimated Page Count:

~2000+

Type:

Factory Service Manual / Workshop Manual

Language:

English

Format:

Digital Download (PDF)

📖 Manual Coverage

Engine Mechanical:

Detailed disassembly, assembly, inspection, and repair of all engine components including block, heads, pistons, crankshaft, camshafts, valvetrain.

Engine Management:

ECU operation, sensor inputs/outputs, fuel injection, ignition timing, emissions control systems, diagnostic trouble codes (DTCs).

Transmission Drivetrain:

Manual transmission (6-speed), DCCD (Driver Controlled Centre Differential) system, viscous coupling unit, front and rear differentials, driveshafts, hubs.

Suspension Steering:

Front and rear suspension components (struts, springs, control arms, anti-roll bars), power steering system, steering rack, alignment procedures.

Braking System:

Brake system components (rotors, pads, calipers), ABS (Anti-lock Braking System), EBD (Electronic Brakeforce Distribution), brake fluid specifications and bleeding procedures.

Electrical System:

Wiring diagrams, component locations, fuse box layouts, starter, alternator, battery, lighting systems, power accessories, immobilizer system.

HVAC System:

Air conditioning, heating, ventilation system components, refrigerant handling, and servicing.

Body Chassis:

Body panel removal/installation, interior trim, glass, door mechanisms, structural components, rust prevention.

Maintenance Tasks:

Oil and filter changes, air filter replacement, spark plug replacement, coolant flush, brake fluid replacement, differential fluid changes, power steering fluid flush.

Diagnostic Procedures:

Troubleshooting guides based on symptoms, OBD-II scanner usage, sensor testing, electrical circuit diagnosis.

Repair Procedures:

Step-by-step instructions for component removal, repair, and reinstallation, including torque specifications and special tool requirements.

Specifications Data:

Torque values for all fasteners, engine tolerances, fluid capacities, electrical specifications, alignment settings.

Depth:

Expert level, suitable for professional technicians and advanced DIY mechanics. Covers complete vehicle teardown and rebuild.

📊 Manual Specifications

Digital Format:

PDF (Portable Document Format)

Searchability:

Fully searchable text for quick access to information.

Print Compatibility:

Optimized for printing, with clear diagrams and text.

Binding:

Not Applicable (Digital Download)

Paper Quality:

Not Applicable (Digital Download)

⚙️ Engine Specifications

Engine Type:

EJ257 Turbocharged Boxer-4

Displacement:

2.5 Liters (2457 cc)

Bore X Stroke:

99.5 mm x 80.0 mm

Compression Ratio:

8.2:1

Valve Mechanism:

DOHC (Dual Overhead Camshafts), 16 Valves

Horsepower:

305 hp @ 6000 rpm

Torque:

290 lb-ft (393 Nm) @ 4000 rpm

Fuel Type:

Premium Unleaded Gasoline (91 Octane or higher recommended)

Fuel Delivery:

Sequential Multi-Point Fuel Injection (S-MPI)

Turbocharger:

Twin-Scroll Turbocharger with Intercooler

🔧 Transmission

Type:

6-Speed Manual Transmission

Dccd:

Driver Controlled Centre Differential (DCCD) with automatic and manual modes.

Optional Transmission:

None for WRX STI model in 2015

Clutch Type:

Hydraulically actuated, single-plate, dry type

Final Drive Ratio:

3.55:1

📐 Dimensions

Length:

180.9 inches (4595 mm)

Width:

70.7 inches (1796 mm)

Height:

57.9 inches (1471 mm)

Wheelbase:

104.1 inches (2645 mm)

Front Track:

60.6 inches (1539 mm)

Rear Track:

61.0 inches (1550 mm)

Curb Weight:

~3373 lbs (1530 kg)

Gross Vehicle Weight Rating:

4630 lbs (2100 kg)

Towing Capacity:

Not Recommended / Not Specified

Trunk Volume Sedan:

11.3 cubic feet (0.32 m³)

Cargo Volume Hatchback:

20.1 cubic feet (0.57 m³) (with rear seats up)

🛡️ Safety Features

NHTSA Overall Rating:

4 out of 5 Stars (for comparable models/years)

ABS:

Standard Anti-lock Braking System

Ebd:

Standard Electronic Brakeforce Distribution

Vsc:

Standard Vehicle Stability Control (VSC) with Sport Mode

Traction Control:

Standard Traction Control System (TCS)

AWD:

Standard Symmetrical All-Wheel Drive

Airbags:

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

Seatbelts:

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

Child Anchors:

LATCH (Lower Anchors and Tethers for CHildren) system

Body Structure:

Advanced front crumple zone and Ring-Structure reinforced passenger compartment.

💡 Technology Features

Head Unit:

Standard touchscreen infotainment system with Bluetooth, USB, and auxiliary input. Optional navigation system.

Audio System:

Standard 6-speaker audio system. Upgraded Harman Kardon system available on some trims.

Rear View Camera:

Standard

Other Features:

Keyless entry and push-button start, multi-function display in instrument cluster.

Bluetooth:

Standard for hands-free calling and audio streaming.

🔧 Maintenance

Oil Change Interval:

Every 3,750 miles (6,000 km) or 6 months, whichever comes first, under severe driving conditions (performance driving, towing, short trips); 7,500 miles (12,000 km) or 12 months under normal conditions. However, synthetic oil is highly recommended for STI models.

Engine Air Filter:

Inspect every 15,000 miles (24,000 km), replace as needed. Recommended replacement every 30,000 miles (48,000 km).

Cabin Air Filter:

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

Spark Plugs:

Replace every 30,000 miles (48,000 km) due to high performance demands. Iridium-tipped plugs are standard.

Coolant Replacement:

First replacement at 105,000 miles (170,000 km), then every 52,500 miles (85,000 km) thereafter.

Brake Fluid Replacement:

Every 30,000 miles (48,000 km) or 24 months, whichever comes first.

Engine Oil:

SAE 5W-30, API SN, ILSAC GF-5 (or equivalent synthetic).

Engine Oil Capacity:

5.8 US quarts (5.5 Liters) with filter change.

Transmission Fluid:

API GL-4 SAE 75W-90 Synthetic Gear Oil (for 6-speed manual transmission).

Differential Fluid Front Rear:

API GL-5 SAE 75W-90 Synthetic Gear Oil.

Coolant:

Subaru Super Coolant (Blue) or equivalent ethylene glycol-based coolant with Subaru's specific additive package.

Brake Fluid:

DOT 3 or DOT 4 brake fluid.

Piston Ring Land Cracks:

While the EJ257 is robust, aggressive driving or insufficient cooling can lead to ring land damage. Regular maintenance and proper oil levels are crucial.

Head Gasket Leaks:

Less common on later EJ series engines compared to earlier generations, but still a potential issue if maintenance is neglected or engine overheats.

Clutch Wear:

Due to the performance-oriented nature and AWD system, clutch wear can be accelerated with aggressive driving.

Turbocharger Wear:

Proper warm-up and cool-down procedures are essential for turbocharger longevity. Oil contamination can also lead to premature wear.

Suspension Bushings:

Performance tuning often leads to increased stress on suspension bushings, which may require replacement sooner than on standard models.

📚 Vehicle History

Rally Roots:

Subaru's legendary WRC (World Rally Championship) success directly influenced the development of the WRX and STI models.

Generation Notes:

The 2015 model marked a significant redesign, moving to the Subaru Global Platform (shared with other Impreza models), but retained the EJ257 engine and distinctive STI character. This generation saw the discontinuation of the hatchback body style in North America for the STI.

Production Years:

WRX STI: 1992–Present (Globally); 2004–Present (North America)

Manufacturing Location:

Japan (Ōta, Gunma Prefecture)

🏆 Awards & Recognition

Car And Driver 10Best:

While the WRX STI itself isn't typically on the 10Best list (which often favors broader appeal), the Impreza WRX variant has made multiple appearances, indicating the platform's inherent capabilities.

Consumer Reports:

Historically, the STI has received mixed reviews for reliability compared to some competitors, often due to its high-performance nature and specialized components. However, owner satisfaction for performance and handling is typically very high.