Segment:
Performance Compact Sedan/Hatchback, Rally-Inspired Sport Compact
Competitors:
Mitsubishi Lancer Evolution, Subaru WRX (non-STI variants), Ford Focus RS (later models), Volkswagen Golf R.
Performance Highlights:
Symmetrical All-Wheel Drive, turbocharged Boxer engine, Driver Controlled Center Differential (DCCD), performance suspension and brakes.
Target Audience:
Enthusiasts seeking high-performance, all-weather capable, and customizable vehicles.
Engine:
EJ257 (2.5L Turbocharged Boxer), including tuning, diagnostics, and component repair.
Transmission:
6-speed manual (Type RA) and DCCD (Driver Controlled Center Differential) system.
Drivetrain:
All-Wheel Drive (Symmetrical AWD), front/rear differentials, driveshafts, CV joints.
Suspension:
Front/rear suspension components, spring rates, damper specifications, alignment procedures.
Brakes:
Brembo 4-piston front/2-piston rear brake system, ABS, EBD, brake fluid bleeding, component replacement.
Electrical:
Complete wiring diagrams, ECU, sensors, lighting, power distribution, starter, alternator, battery.
Fuel System:
Fuel injectors, fuel pump, fuel pressure regulator, EVAP system, emissions control.
Cooling System:
Radiator, intercooler, coolant hoses, water pump, thermostat, system flush.
Exhaust System:
Turbocharger, downpipe, catalytic converter, mufflers, heat shields.
Body And Chassis:
Body panels, doors, fenders, bumpers, underbody, chassis reinforcement.
Interior:
Seats, dashboard, trim panels, HVAC controls, SRS airbag system.
HVAC:
Air conditioning system, heater core, blower motor, climate control diagnostics.
Diagnostics:
OBD-II diagnostics, fault code interpretation, sensor data analysis, troubleshooting guides.
Maintenance:
Oil changes, filter replacements, spark plug replacement, fluid checks and flushes, belt inspection/replacement.
Engine Repair:
Timing belt/chain service, piston/ring replacement, head gasket repair, valve adjustments, turbocharger rebuild.
Transmission Repair:
Clutch replacement, gearbox rebuild, DCCD actuator servicing.
Brake Repair:
Brake pad/rotor replacement, caliper servicing, brake line replacement, ABS component diagnostics.
Electrical Repair:
Wiring harness repair, sensor replacement, starter/alternator replacement, ECU troubleshooting.
Suspension And Steering:
Strut/shock replacement, control arm replacement, wheel bearing replacement, power steering system service.
Troubleshooting:
Step-by-step diagnostic procedures for common and uncommon issues.
Component Replacement:
Detailed instructions for replacing virtually all serviceable parts.
Bodywork And Trim:
Removal and installation of interior and exterior trim components, body panel adjustments.
Depth:
Comprehensive, from basic maintenance to complete engine and transmission rebuilds. Includes factory diagnostic procedures and specifications.
NHTSA Overall Rating:
4/5 Stars (for 2012 model, specific STI ratings may vary)
Active Safety:
Vehicle Dynamics Control (VDC), Traction Control System (TCS), Anti-lock Braking System (ABS), Electronic Brake-force Distribution (EBD), Active Torque Split AWD.
Passive Safety:
Frontal airbags, front side-impact airbags, side curtain airbags, driver's knee airbag, front seatbelt pretensioners, active front head restraints.
Infotainment System:
Subaru's Starlink infotainment system with touchscreen, Bluetooth, USB connectivity, optional navigation.
Driver Assistance Features:
Key features focus on performance dynamics: Traction Control, VDC, DCCD. Advanced driver-assistance systems (ADAS) like EyeSight were not standard or widely available on the STI during these model years.
Connectivity Options:
Bluetooth hands-free calling, audio streaming, USB port for media playback and charging.
Oil Change Interval:
Every 3,750 miles or 3 months (severe driving) / 7,500 miles or 7.5 months (normal driving).
Engine Air Filter:
Inspect every 15,000 miles, replace as needed. Replace every 30,000 miles under normal conditions.
Cabin Air Filter:
Replace every 15,000 miles or annually.
Spark Plugs:
Replace every 30,000 miles (NGK SILFR6A iridums recommended).
Coolant Flush:
Initial flush at 60,000 miles, then every 30,000 miles thereafter. Subaru Super Coolant (Blue).
Engine Oil Type:
5W-30 Synthetic (API SN or higher)
Engine Oil Capacity:
5.1 US Quarts (4.8 Liters) with filter change
Brake Fluid Type:
DOT 3 or DOT 4
Engine Potential Issues:
Head gasket failures (though less common on EJ257 than earlier EJ25 variants), piston ring land failures from detonation, turbocharger oil starvation, oil consumption.
Clutch Wear:
High-performance clutch can wear faster under aggressive driving.
Dccd Faults:
DCCD unit or related sensors can fail, leading to warning lights or drivetrain issues.
