Subaru Impreza Common Problems & Reliability Guide
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Overview
The Subaru Impreza is a compact car known for its standard all-wheel drive system and boxer engine. While generally reliable, it has experienced issues with head gaskets, CVT transmissions, and various sensor failures across generations. The WRX and STI performance variants share the platform but have unique issues related to their turbocharged engines.
Quick Summary
By Generation
Available Engines
Common OBD2 Codes
| Code | Frequency | Notes |
|---|---|---|
| P0420 | Very Common | Catalyst system efficiency below threshold - often due to failing catalytic converter or O2 sensors |
| P0325 | Common | Knock sensor circuit malfunction - sensor or wiring harness failure |
| P0441 | Common | EVAP system incorrect purge flow - often purge valve or leak in system |
| P0304 | Common | Cylinder 4 misfire - often related to head gasket failure on this cylinder |
| P0171 | Occasional | System too lean - MAF sensor contamination or vacuum leaks common |
Known Problems
External head gasket leaks causing coolant seepage are extremely common on 2.5L EJ25D engines. Look for white residue around cylinder heads and coolant loss without visible leaks. Can progress to internal failure causing overheating.
Typical mileage: 80,000-120,000
Shop parts for this repairCatalytic converters deteriorate prematurely, especially on California emissions models. Causes poor fuel economy, reduced power, and failed emissions tests.
Typical mileage: 100,000-150,000
Shop parts for this repairManual transmission models develop noisy throwout bearings causing grinding or squealing when clutch pedal is depressed. Requires transmission removal to replace.
Typical mileage: 60,000-100,000
Shop parts for this repairFront wheel bearings wear prematurely causing humming or grinding noise that increases with speed. Common on all-wheel drive models due to additional stress.
Typical mileage: 70,000-120,000
Shop parts for this repairEvaporative emissions system develops leaks in hoses, purge valve, or gas cap seal. Causes check engine light and failed emissions tests.
Typical mileage: 80,000-150,000
Shop parts for this repairAvailable Engines
Common OBD2 Codes
| Code | Frequency | Notes |
|---|---|---|
| P0420 | Very Common | Catalyst efficiency - extremely common on 2.5L engines, often both banks |
| P0325 | Very Common | Knock sensor 1 malfunction - harness failure extremely common, located under intake |
| P0328 | Common | Knock sensor 2 circuit high - same harness issue as P0325 |
| P0507 | Common | Idle control system RPM higher than expected - throttle body carbon buildup or IAC valve |
| P0171 | Common | System too lean - MAF sensor failure or intake boot cracks common |
| P0304 | Occasional | Cylinder 4 misfire - head gasket or ignition coil failure |
Known Problems
2002-2005 models with 2.5L EJ251 engines are notorious for external head gasket leaks. Improved gaskets introduced in 2006 but issue still present. External leaks show as coolant weeping between head and block. Can lead to internal failure if ignored.
Typical mileage: 60,000-100,000
Shop parts for this repairKnock sensor wiring harness located under intake manifold deteriorates from heat exposure. Insulation becomes brittle and shorts against engine block. Requires intake manifold removal to replace.
Typical mileage: 80,000-150,000
Shop parts for this repairTurbochargers on WRX and STI models can fail due to oil starvation, bearing wear, or boost control issues. Symptoms include excessive smoke, loss of power, and loud whining noise. Modified vehicles especially prone.
Typical mileage: 80,000-150,000
2002-2005 WRX models with 5-speed manual transmission experience gear grinding in 2nd and 3rd gears due to synchronizer wear. Some cases result in complete transmission failure.
Typical mileage: 60,000-120,000
Shop parts for this repairExcessive oil consumption due to worn piston rings, especially on turbocharged models. Engines may consume 1 quart per 1,000 miles or more. Can lead to engine damage if not monitored.
Typical mileage: 100,000-180,000
Shop parts for this repairRear wheel bearings fail prematurely causing humming noise that varies with speed. More common on WRX/STI due to increased power and torque.
Typical mileage: 60,000-100,000
Shop parts for this repairStrut top mounts deteriorate causing clunking noise over bumps and poor steering response. Rubber bushings crack and separate.
Typical mileage: 80,000-120,000
Shop parts for this repairRecalls
Brake light switch may fail, preventing brake lights from illuminating and disabling cruise control. Creates rear-end collision risk.
Yellow sac spiders may build webs in vent line, causing fuel tank pressure issues and potential cracking. Affects multiple model years 2005-2009.
WRX STI models may have ignition coil wires separate from terminals, causing misfires or engine stalling.
Available Engines
Common OBD2 Codes
| Code | Frequency | Notes |
|---|---|---|
| P0420 | Very Common | Catalyst system efficiency - both banks commonly fail by 100k miles |
| P0325 | Very Common | Knock sensor 1 malfunction - harness still failing on this generation |
| P0351 | Common | Ignition coil A primary/secondary circuit - coil pack failure common |
| P0607 | Common | Control module performance - ECU internal fault, often requires replacement |
| P0456 | Common | EVAP system small leak - gas cap or hose leaks |
| P0506 | Occasional | Idle control system RPM lower than expected - throttle body issues |
Known Problems
While improved over previous generation, 2008-2009 2.5L engines still experience external head gasket leaks. 2010-2011 models have significantly improved gasket design but not immune. Look for coolant weeping and white residue.
Typical mileage: 100,000-150,000
Shop parts for this repairEngine control units develop internal faults causing various symptoms including no-start, rough idle, stalling, and multiple fault codes. Issue affects both turbo and non-turbo models. Remanufactured ECUs often the only solution.
Typical mileage: 80,000-150,000
Shop parts for this repair2011-2014 2.5L engines consume excessive oil due to worn piston rings. Subaru issued extended warranty for some VINs. Engines may consume 1 quart per 1,000-3,000 miles. Can lead to engine damage.
Typical mileage: 60,000-120,000
Shop parts for this repairWRX models develop wastegate rattle at idle or low RPM due to worn wastegate actuator arm or loose flapper valve. Usually cosmetic but can indicate turbo wear.
Typical mileage: 40,000-80,000
Shop parts for this repairManual transmission throw-out bearings fail causing grinding or squealing noise when clutch pedal is pressed. Common failure point requiring transmission removal.
Typical mileage: 60,000-100,000
Shop parts for this repairCV axle boots tear allowing grease to escape and contamination to enter. Causes clicking noise during turns if left too long. Regular inspection recommended.
Typical mileage: 80,000-120,000
Shop parts for this repairRecalls
Continuation of brake light switch issue from previous generation. Switch may fail preventing brake lights from working.
Takata airbag inflator recall. Inflator may rupture causing metal fragments to spray into cabin. Multiple recalls issued.
Available Engines
Common OBD2 Codes
| Code | Frequency | Notes |
|---|---|---|
| P0420 | Common | Catalyst efficiency - less common on FB20 but still occurs |
| P0301 | Common | Cylinder 1 misfire - often due to carbon buildup on intake valves (direct injection) |
| P0171 | Common | System too lean bank 1 - MAF sensor or intake leaks |
| P0138 | Common | O2 sensor circuit high voltage bank 1 sensor 2 - downstream O2 failure |
| P0456 | Occasional | EVAP system small leak detected - gas cap or purge valve |
| P0304 | Occasional | Cylinder 4 misfire - carbon buildup or ignition coil |
| P219A | Occasional | Bank 1 air/fuel ratio imbalance - often related to carbon buildup |
Known Problems
CVT-equipped models experience shuddering or juddering during acceleration, especially at low speeds. Often caused by torque converter lockup clutch wear. Subaru issued extended warranty and software updates for affected units.
Typical mileage: 30,000-80,000
Shop parts for this repair2012-2015 FB20 engines consume excessive oil due to piston ring design. Subaru extended warranty to 8 years/100,000 miles for eligible VINs. Consumption test required for warranty coverage.
Typical mileage: 40,000-100,000
Shop parts for this repairFront wheel bearings develop noise earlier than expected, causing humming or growling that varies with speed. Left side more commonly affected.
Typical mileage: 50,000-90,000
Shop parts for this repairPower steering racks develop leaks from seals causing fluid loss and potential steering difficulty. Leaks usually at bellows or end seals.
Typical mileage: 80,000-130,000
Shop parts for this repairWRX manual transmission clutches wear prematurely, especially with spirited driving. Clutch material breakdown causes slipping and poor engagement. Lightweight flywheel conversions common.
Typical mileage: 40,000-80,000
Shop parts for this repairWindshields develop stress cracks from cowl/frame flex, often starting at lower corners. Manufacturing defect acknowledged by Subaru for some years.
Typical mileage: Any
Shop parts for this repairStarlink infotainment system freezes, reboots randomly, or becomes unresponsive. Software updates available but don't always resolve issue. Touchscreen may also delaminate.
Typical mileage: Any
Shop parts for this repairRecalls
Passenger frontal airbag inflator may explode during deployment. Massive multi-year recall affecting millions of vehicles.
Brake lamp switch may fail due to insufficient grease, preventing brake lights from working and disabling cruise control.
WRX and STI models with PCV valve assembly may allow engine oil to leak onto hot exhaust, creating fire risk.
Available Engines
Common OBD2 Codes
| Code | Frequency | Notes |
|---|---|---|
| P0420 | Common | Catalyst efficiency - still occurs on FB20, less common on FA20 |
| P0301 | Common | Cylinder 1 misfire - carbon buildup on direct injection engines |
| P0171 | Common | System too lean - MAF sensor or intake system leaks |
| P0456 | Common | EVAP small leak - commonly gas cap or purge valve |
| P0172 | Occasional | System too rich - often MAF sensor or fuel pressure regulator |
| P0451 | Occasional | EVAP pressure sensor range/performance - sensor failure |
| P219A | Occasional | Air/fuel ratio cylinder imbalance - carbon buildup related |
Known Problems
CVT transmissions continue to experience shuddering, hesitation, and complete failure. Linear solenoid valve, torque converter, and valve body failures common. Multiple software updates released but issues persist in some units.
Typical mileage: 40,000-100,000
Shop parts for this repairFB20 and FA20 direct injection engines develop significant carbon deposits on intake valves. Causes misfires, rough idle, hesitation, and reduced fuel economy. Walnut blasting service recommended every 60-80k miles.
Typical mileage: 50,000-90,000
Shop parts for this repairTouchscreen infotainment systems freeze, reboot, or become completely unresponsive. Backup camera may fail intermittently. Software updates help but hardware replacement often needed. Screen delamination also common.
Typical mileage: 30,000-80,000
Shop parts for this repairEyeSight driver assistance system experiences false warnings, calibration issues, and component failures. Windshield replacement requires expensive recalibration. Front camera failure common on earlier models.
Typical mileage: 40,000-100,000
Shop parts for this repairContinued oil consumption issues on 2017-2019 FB20 engines. Some improvement over previous generation but still present. Extended warranty coverage available for some VINs.
Typical mileage: 50,000-120,000
Shop parts for this repairWindshields crack easily from minor road debris and develop stress cracks. Issue particularly bad on 2017-2018 models. EyeSight-equipped vehicles require expensive OEM windshield and recalibration.
Typical mileage: Any
Shop parts for this repairAir conditioning compressors fail prematurely, often due to clutch bearing or internal seal failure. Symptom is no cold air or loud grinding noise from compressor.
Typical mileage: 60,000-120,000
Shop parts for this repairWRX FA20 turbo engines can develop rod knock from bearing failure, often without warning. Issue linked to oil starvation during hard cornering and quality of OEM bearings. Many cases under 60k miles.
Typical mileage: 30,000-80,000
Recalls
Rear suspension subframe may corrode in salt belt states, potentially causing component separation. Recall involves inspection and replacement if necessary.
2019 Ascent, Impreza, and Legacy models with FB25 engine may have defective valve springs causing engine stalling or failure to start.
Ignition coil connector may not be fully seated, causing engine misfires, stalling, or failure to start.
Available Engines
Common OBD2 Codes
| Code | Frequency | Notes |
|---|---|---|
| P0456 | Common | EVAP small leak - gas cap or purge valve on new vehicles |
| P0171 | Occasional | System too lean - MAF sensor or intake issues |
| P0301 | Occasional | Cylinder 1 misfire - ignition coil or carbon buildup developing |
| P0420 | Occasional | Catalyst efficiency - less common on newer vehicles but can occur |
Known Problems
Some early 2024 models report CVT hesitation during acceleration and occasional shuddering. Subaru has released software updates to address behavior. Monitor for continued development of earlier CVT issues.
Typical mileage: 5,000-30,000
New generation Starlink system experiences occasional freezing, slow response, and connectivity issues. Wireless CarPlay/Android Auto connection drops reported. Software updates being released.
Typical mileage: Any
Shop parts for this repairReports of thin paint and premature chipping on front bumper, hood, and fenders. Clear coat peeling on some units. Quality control issue on early production vehicles.
Typical mileage: Any
Shop parts for this repairUpdated EyeSight 4.0 system occasionally requires recalibration or throws false warnings. System may disable itself temporarily after windshield cleaning or in certain weather conditions.
Typical mileage: Any
Shop parts for this repairRecalls
Engine harness ground connection may not be properly secured, potentially causing various electrical issues or engine stalling.