Skip to content
KickTyres
Subaru1992–2023 Critical issues documented

Subaru STI: common faults & what to check

Thinking about buying a used Subaru STI (1992–2023) in New Zealand? We've documented 32 known faults for this model spanning engine, transmission, cooling, and body & rust. Each researched and verified before it's published. The most serious issues here are rated critical. Every one is listed below with its symptoms and repair cost, and each has its own page with where to look and what to ask the seller. Free, no account needed.

Check this exact Subaru STI

  • Odometer history
  • Money owing
  • Reported stolen
  • Ownership history
  • Official NZ vehicle register data
  • NZ owned and operated

Type the plate for the free basics. The full record is a paid check from $13.49, one car at a time, no subscription.

No NZ plate yet, or buying in Australia? Pick the generation and engine and start a free check below. New to KickTyres? How the check works →

32

Documented faults

Critical

Most serious

$600–$2,800

Typical repair

8

Systems covered

Which Subaru STI are you looking at?

5 generation variants documented. Pick the shape you recognise: the faults, the servicing and the timeline below all narrow to it. Free, no account needed.

Now narrow it to the engine

A 1.8 and a 2.4 of the same car do not fail the same way, so the faults below narrow to the engine as well as the year. Free, no account needed.

Start your free check on this Subaru STI

No plate needed. You get the risk score, the buyer's checklist and the guided inspection for the exact car you picked above — not the whole nameplate.

Subaru STIEngine not picked yet

Pick the engine above first: the STI came with 5, and without it the report has to show all of their faults. Pick the engine

Free. The paid plate check is separate, and stays optional.

Can't confirm for this car

Subaru STI

Nothing has been narrowed yet, so nothing below is a claim about a particular car. Pick a year and an engine to see which faults apply.

Tell us the engine, or check the engine code on the car, before relying on this.

matched on no vehicle context

What to look out for

The checks worth doing on a Subaru STI before you hand over any money. Every documented fault is listed below, each with its own page.

  • Serious issue

    Inspect coolant reservoir for brown oily residue or emulsification.

    See why

    EJ25 STI Head Gasket Failure

    The EJ25 2.5-litre turbocharged flat-four used in WRX STI models has a well-documented multi-layer steel (MLS) head gasket failure pattern, most pronounced on the rear cylinder on each bank. The combination of high cylinder pressures, a wide bore, and aluminium heads on a cast-iron block produces differential thermal expansion that causes the head gasket to weep or blow — typically between coolant and oil passages, or externally. Failure accelerates on vehicles that have been driven hard, run lean, or have experienced any overheating episode. The factory torque-to-yield head bolts further complicate repair, as they must be replaced on reassembly.

    What you would notice

    • Coolant loss without visible external leak — coolant is consumed into combustion chamber
    • White sweet-smelling steam from exhaust, particularly after the engine reaches operating temperature
    • Brown or milky contamination in coolant reservoir or on oil dipstick
    • Overheating or fluctuating temperature gauge, especially under load
    • Rough running or misfires on one or more cylinders due to coolant entering combustion

    Typically $3,200–$7,500 to put right.

  • Serious issue

    Check the coolant overflow bottle for brown oily scum at the waterline.

    See why

    EJ20 Phase 1 Head Gasket Failure (GC/GF 2.0T)

    The first-generation EJ20 turbo uses a single-layer metal shim head gasket poorly suited to the thermal cycling of turbocharged use, leading to coolant and combustion gas leaks predominantly between cylinders 2 and 3. Failure is accelerated by overheating events, deferred coolant flushes, or sustained boost use. Consequences range from coolant loss and white exhaust smoke to catastrophic hydro-lock if coolant enters a cylinder. This is considered near-universal on unmodified high-kilometre GC/GF examples and is one of the most extensively documented faults across all Subaru WRX forums worldwide.

    What you would notice

    • White or sweet-smelling exhaust smoke when warmed up
    • Coolant loss with no visible external leak
    • Milky or frothy residue on oil dipstick or filler cap
    • Overheating gauge fluctuation under load
    • Bubbles or oily scum in coolant reservoir

    Typically $1,800–$3,800 to put right.

  • Serious issue

    Pull the oil dipstick and inspect for silver metallic debris or sludge.

    See why

    EJ257 Piston Ringland Failure

    The EJ257 boxer engine uses a closed-deck block with relatively thin piston crown ringlands. Under sustained high boost pressure (stock or modified), the third and fourth piston ringlands crack due to the combination of high cylinder pressures, detonation events from heat soak, and the lateral combustion forces inherent in a horizontally-opposed layout. Cylinder 4 is disproportionately affected because it runs hotter (end of the intake manifold, less fuel cooling). Ethanol blends, aggressive ignition timing, and pump fuel in hot ambient conditions accelerate ringland cracking. Once a ringland fractures, broken ring fragments score the bore walls and contaminate the oil system with aluminium debris, typically requiring a full short-block replacement.

    What you would notice

    • Engine knock or tick on cold start that worsens under load
    • White or grey smoke from exhaust under boost
    • Loss of power and boost pressure on one cylinder
    • Low or uneven compression reading on cylinder 4
    • Oil contamination with metallic silver particles
    • Check engine light with cylinder-specific misfire codes

    Typically $7,500–$18,000 to put right.

  • Serious issue

    Check the oil filler cap underside for creamy emulsion or sludge that suggests poor maintenance.

    See why

    EJ Spun Rod Bearing from Oil Starvation

    The EJ-series boxer engines use a wet-sump lubrication system with a laterally positioned oil pickup that is susceptible to oil starvation during sustained high-lateral-G cornering or hard braking. Under these conditions, oil sloshes away from the pickup tube, causing momentary oil pressure drops. The connecting rod bearings — already running tight clearances on the stock specification — suffer micro-seizure events that progressively wipe the bearing shell. Accumulated wear debris then circulates through the oil system, accelerating main bearing and crankshaft journal damage. Oil that has been extended beyond change intervals, run low on quantity, or degraded from heat cycling has reduced film strength that compounds this failure mode. The number 4 rod bearing is statistically the first to fail on right-hand-drive cars driven on left-hand corners.

    What you would notice

    • Deep rhythmic knocking noise that increases with engine RPM
    • Sudden oil pressure warning light activation during cornering
    • Rattling or rumbling from lower engine block at idle
    • Oil with a metallic sheen or copper-coloured particles
    • Engine shudder under hard acceleration

    Typically $6,000–$15,000 to put right.

  • Serious issue

    Check the oil on the dipstick for milky or cream-coloured emulsification indicating coolant mixing with oil.

    See why

    EJ207 Head Gasket Failure Between Coolant and Oil

    The EJ207 2.0T STI boxer engine is prone to head gasket failure between the coolant and oil passages at high mileage or after overheating events. Coolant and oil cross-contaminate, causing rapid engine damage if not detected promptly.

    What you would notice

    • Milky or cream-coloured emulsification on the oil dipstick from coolant contamination
    • Coolant level dropping without a visible external leak as coolant enters the oil system

    Typically $2,000–$6,000 to put right.

  • Serious issue

    Monitor the coolant temperature gauge closely during a sustained test drive under load, including hills.

    See why

    EJ20/EJ205 Water Pump Plastic Impeller Failure (GC/GF and GD/GG)

    Subaru's factory water pump on EJ-series engines uses a plastic impeller that degrades and spins free on its shaft over time, dramatically reducing coolant flow without triggering any visible external leak. The failure is insidious — the pump still turns and appears normal externally, but coolant is barely circulating, leading to gradual or sudden overheating. An overheating event in an EJ Subaru with a failed impeller frequently precedes head gasket failure. The pattern is documented across GC/GF and GD/GG WRX and STI models spanning 1994 to 2007. Replacement with an aftermarket metal-impeller unit is the accepted long-term fix.

    What you would notice

    • Gradual or intermittent engine overheating with no visible coolant leak
    • Temperature gauge creeping high under sustained load
    • Coolant level dropping with no visible external leak
    • Overheating events that cool once stationary (fan working but coolant not circulating)

    Typically $450–$950 to put right.

See all 32 documented issuesEverything researched for the Subaru STI, including 8 rated critical.
Depends on which engine this Subaru STI has — 31Each of these is documented for one particular engine. Pick the year and engine above to see which of them apply.
Engine, transmission & cooling19

01EJ257 Piston Ringland Failure

Pull the oil dipstick and inspect for silver metallic debris or sludge.petrol2001–2021EngineRead the full fault: symptoms, where to look, what to ask the seller

02EJ Spun Rod Bearing from Oil Starvation

Check the oil filler cap underside for creamy emulsion or sludge that suggests poor maintenance.petrol2001–2021EngineRead the full fault: symptoms, where to look, what to ask the seller

03EJ257 2.5T Connecting Rod Bearing Failure at High Mileage (GD/GG and GE/GH STI)

Listen carefully at idle and through the full rev range for a deep, rhythmic knocking sound that increases with engine speed.petrol2012–2014Engine
OccasionalEngine $4,500–$10,000 to fix

Can't confirm for this car

At higher mileages (typically above 150,000 km), EJ257 engines are susceptible to connecting rod bearing wear that can progress rapidly to spun bearings and catastrophic engine failure. The failure is linked to oil viscosity breakdown from extended service intervals, oil starvation under hard cornering at low oil levels, and inherent crankshaft journal finish tolerances in the EJ257 short block. Subaru issued extended powertrain warranty provisions in some export markets specifically acknowledging the rod bearing failure pattern on high-mileage STIs. The knocking onset can be rapid, and continued driving after first signs of knock results in total engine destruction requiring short-block replacement.

Symptoms to notice

  • Deep low-frequency knocking or rumbling from the engine under load
  • Knock most pronounced under hard acceleration or immediately after cold start
  • Oil pressure warning light illuminating at idle on worn examples
  • Metal particles or debris in oil at service drain

What to check

  1. Listen carefully at idle and through the full rev range for a deep, rhythmic knocking sound that increases with engine speed.
  2. Check the oil service history for any evidence of extended intervals beyond 5,000 km.
  3. Verify current oil level and condition.
  4. If a workshop inspection is possible: If the seller can provide oil analysis results, look for elevated iron and copper levels indicating bearing wear.

Where to look: EJ257 short block connecting rod big-end bearings and crankshaft main journals

Ask the seller

  • “What oil change intervals has this car been run on consistently?”
  • “Has any engine knock or tapping ever been noticed?”
  • “Has the car been used for track days where oil starvation under lateral G-forces could occur?”

04EJ25 STI Head Gasket Failure

Inspect coolant reservoir for brown oily residue or emulsification.petrol2014–2021EngineRead the full fault: symptoms, where to look, what to ask the seller

05EJ207 Head Gasket Failure Between Coolant and Oil

Check the oil on the dipstick for milky or cream-coloured emulsification indicating coolant mixing with oil.petrol2014 onwardEngine
CommonEngine $2,000–$6,000 to fix

Can't confirm for this car

The EJ207 2.0T STI boxer engine is prone to head gasket failure between the coolant and oil passages at high mileage or after overheating events. Coolant and oil cross-contaminate, causing rapid engine damage if not detected promptly.

A removed multi-layer steel head gasket held up, showing staining around the cylinder bore.Example of the part — not this vehicle

A used multi-layer head gasket. Discolouration between a cylinder and a water gallery is the tell.

John Furman · CC BY-SA 3.0 · Wikimedia Commons

Symptoms to notice

  • Milky or cream-coloured emulsification on the oil dipstick from coolant contamination
  • Coolant level dropping without a visible external leak as coolant enters the oil system

What to check

  1. Check the oil on the dipstick for milky or cream-coloured emulsification indicating coolant mixing with oil.
  2. Check the coolant expansion tank for oily residue.
  3. Perform a combustion gas test on the coolant.

Where to look: Cylinder head gaskets on both heads of the EJ207 boxer engine

Parts involved: Head gasket.

Ask the seller

  • “Has the ej207 head gasket failure between been inspected or repaired?”

06EJ20 Phase 1 Head Gasket Failure (GC/GF 2.0T)

Check the coolant overflow bottle for brown oily scum at the waterline.petrol1994–2000EngineRead the full fault: symptoms, where to look, what to ask the seller

07EJ20/EJ257 AVCS Cam Gear Retaining Bolt Loosening

Retrieve any stored fault codes - AVCS cam position errors are a strong indicator.petrol2000–2011Engine
OccasionalEngine $600–$2,200 to fix

Can't confirm for this car

Subaru's Active Valve Control System (AVCS) variable valve timing uses a cam gear secured by a central retaining bolt. On EJ205, EJ20X, EJ20Y, and EJ257 engines (GD/GG and GH/GR generations), this bolt is known to back out under sustained high-RPM operation. A loose cam gear causes incorrect valve timing, rough running, and if it backs out fully can cause the cam gear to spin on the camshaft, resulting in catastrophic timing failure. Documented across multiple continents with specific torque re-torque service bulletins issued.

Symptoms to notice

  • Rough idle that worsens when warm
  • Poor throttle response or hunting idle
  • Check engine light with cam position sensor codes (P0011, P0021 or similar)
  • Rattling or ticking from cam timing area on startup
  • Loss of power across the rev range

What to check

Retrieve any stored fault codes - AVCS cam position errors are a strong indicator. If accessible, check cam gear bolt torque (Subaru issued re-torque guidance). Listen for timing chain or gear rattle on cold start. Check service history for any AVCS-related work.

Where to look: Intake camshaft AVCS gear on each cylinder bank, accessible from the cam cover area

Ask the seller

  • “Has the AVCS cam gear bolt ever been inspected or re-torqued?”
  • “Are there any check engine lights or stored fault codes?”
  • “Has the car had any rough idle or hesitation issues?”

08EJ20/EJ205 Water Pump Plastic Impeller Failure (GC/GF and GD/GG)

Monitor the coolant temperature gauge closely during a sustained test drive under load, including hills.petrol1994–2007CoolingRead the full fault: symptoms, where to look, what to ask the seller

09STI DCCD Front Differential Clutch Pack Wear

Check the DCCD mode indicator on the dashboard functions through all manual lock positions.petrol2004–2021Transmission
OccasionalTransmission $2,200–$5,500 to fix

Can't confirm for this car

The STI's Driver-Controlled Centre Differential (DCCD) uses a mechanical Torsen element combined with an electromagnetic clutch pack to vary front-to-rear torque split. The clutch pack friction discs wear progressively under aggressive driving, track use, and when the differential is operated in a fully-locked manual mode for extended periods. Contaminated differential fluid — particularly fluid that has absorbed moisture or been diluted by coolant from an upstream failure — accelerates friction material degradation. Worn clutch packs produce inconsistent torque transfer, causing understeer/oversteer switching during corner exit, and eventually the electromagnetic actuator cannot achieve a locked state even at maximum current. The complete DCCD unit replacement is expensive; some specialists can source rebuilt clutch packs but the process requires differential removal.

Symptoms to notice

  • Shuddering or binding when turning at low speed
  • Inconsistent all-wheel-drive behaviour — unexpected understeer on corner exit
  • DCCD warning light illuminated on dashboard
  • Grinding or clicking from centre differential area during tight manoeuvres
  • Differential fluid with a burnt smell or dark colouration

What to check

  1. Check the DCCD mode indicator on the dashboard functions through all manual lock positions.
  2. Drive in a tight carpark figure-eight at low speed and feel for shuddering or binding — healthy DCCD should allow smooth rotation without driveline hop.
  3. Inspect the differential fluid condition — it should be amber-coloured and odour-free.
  4. Confirm fluid change intervals have been observed (every 40,000 km is the recommendation for performance use).

Where to look: Centre differential / transfer case — located at rear of gearbox unit

Parts involved: Differential, Clutch.

Ask the seller

  • “Has the centre differential fluid been changed and at what intervals?”
  • “Has the car been used on a track with the DCCD in manual lock mode?”
  • “Has the DCCD warning light ever appeared?”
  • “Has the differential ever been rebuilt or replaced?”

10Rear Differential Failure Under Hard or Track Use

petrol2014–2023Transmission
OccasionalTransmission $1,500–$4,800 to fix

Can't confirm for this car

The viscous limited-slip rear differential (VLSD) on WRX models and the mechanical Torsen LSD on WRX STI models are known failure points on vehicles that have been driven hard, tracked, or used with mismatched tyre circumferences. The WRX VLSD is particularly sensitive to unequal tyre wear; even modest circumference differences across all four tyres can cause the centre diff and rear diff to fight each other under AWD load, accelerating clutch pack and gear wear. STI Torsen units can fail under sustained track use or drag strip launches, resulting in noisy operation and eventual lockup or loss of rear drive.

Symptoms to notice

  • Howling or whining noise from the rear of the vehicle under steady-state load at 50–100 km/h
  • Clunking from the rear differential on initial acceleration or deceleration
  • Vibration through the floor that correlates with vehicle speed rather than engine RPM
  • Binding or tight steering sensation during slow-speed tight turns, indicating centre diff tension
  • Dark, metallic-smelling differential fluid on inspection

What to check

  1. Check all four tyre tread depths with a gauge — any variance greater than 2 mm across the set is a risk factor and should prompt a diff fluid inspection.
  2. During the test drive, listen for a howling or clunking noise from the rear of the car under light load at 50–80 km/h, which changes with acceleration and deceleration.
  3. Inspect the rear diff casing for oil seepage around the input seal and cover gasket.
  4. Ask specifically whether the car has been on a racetrack or drag strip.

Where to look: Rear differential — mounted at rear axle, driven via rear propshaft from the transfer case

Parts involved: Differential.

Ask the seller

  • “Has the car ever been on a racetrack, drag strip, or used in any competitive driving event?”
  • “Have all four tyres been replaced as a matched set at the same time throughout the car's life?”

11VF39/VF43 Turbo Oil Feed Line Blockage

petrol2001–2021Engine
OccasionalEngine $1,600–$4,800 to fix

Can't confirm for this car

The IHI VF39 (GD/GE WRX and STI) and VF43/VF48 (VA STI) turbochargers are oil-cooled and lubricated via a banjo-bolt oil feed line from the engine oil gallery. Carbon deposits and oxidised oil sludge accumulate in the small-diameter feed line and banjo bolt orifice, progressively restricting oil flow to the turbo centre bearing. At reduced oil supply, the journal bearings run metal-on-metal, generating heat that further cooks the oil in the feed line. This is significantly accelerated by short-trip driving that never fully heats the oil to operating temperature, infrequent oil changes, and switching the engine off immediately after hard high-RPM use without a cool-down period. Initial symptoms are shaft play and boost lag; final failure is centre bearing seizure that can spit the compressor wheel into the intercooler or the turbine wheel into the exhaust.

Symptoms to notice

  • Excessive turbo shaft play felt by hand at the compressor wheel
  • Oil mist or blue smoke from turbo outlet or intercooler connections
  • Boost pressure lag or inconsistent spool up
  • Whining or grinding noise from turbo at boost
  • Oil residue inside the intercooler piping

What to check

With engine cold, reach into the turbo inlet and gently grasp the compressor wheel — there should be zero radial play and minimal axial movement (slight in-out movement is normal). Visually inspect the intercooler inlet hose for oil film inside. Inspect the turbo oil feed banjo bolt and line for any evidence of sludge or restriction. Check for oil leaks at the turbo oil return line and seals.

Where to look: Turbocharger centre housing — oil feed banjo bolt at engine oil gallery and feed line to turbo

Parts involved: Turbocharger.

Ask the seller

  • “Has the turbo oil feed line ever been inspected or replaced?”
  • “What oil change intervals has the car been kept to?”
  • “Has the car been driven hard and then switched off immediately without idling down?”
  • “Has the turbo ever been rebuilt or replaced?”

12EJ20/EJ25 Head Gasket Failure

Check the oil filler cap and dipstick for any creamy or mayonnaise-like emulsion.petrol2001–2014EngineRead the full fault: symptoms, where to look, what to ask the seller

136-Speed Manual 2nd Gear Synchromesh Wear

During a test drive, make multiple brisk 1–2 upshifts and quick 3–2 downshifts.petrol2014–2021Transmission
CommonTransmission $1,800–$4,500 to fix

Can't confirm for this car

The TR580 and TR690 6-speed manual gearboxes used across the WRX and WRX STI lineups exhibit premature synchromesh wear on 2nd gear, and to a lesser extent 3rd gear. The failure presents as a grinding or crunching sensation when engaging 2nd gear, particularly on quick downshifts or aggressive 1–2 upshifts under power. It is exacerbated by spirited driving, clutch-dumping at high RPM, and failure to warm up the transmission oil in cold weather. NHTSA complaints specifically reference 2nd-gear grind on multiple WRX model years. The condition is cumulative and worsens over time if driving style does not change.

Symptoms to notice

  • Grinding or crunching noise when engaging 2nd gear, especially on quick or aggressive shifts
  • Gearbox refusing to slot into 2nd gear and bouncing back to neutral
  • Notchy or baulky feel from the 2nd gear gate that worsens as the transmission warms up
  • Condition improves when shifting slowly but returns under spirited driving
  • Dark or burnt-smelling transmission oil on inspection

What to check

During a test drive, make multiple brisk 1–2 upshifts and quick 3–2 downshifts. Any grinding, crunching, or refusal to engage cleanly indicates synchro wear. Check transmission oil colour and smell — dark, burnt fluid accelerates synchro failure. Ask if the previous owner has changed the transmission fluid and what brand was used (Subaru specifies its own Gear Oil GL-5 75W-90).

Where to look: Gearbox — 2nd gear synchro ring and blocker ring, accessible only with gearbox removal

Parts involved: Clutch.

Ask the seller

  • “Has the transmission oil ever been changed, and if so what product was used and at what mileage?”
  • “Does the gearbox grind or hesitate when engaging 2nd gear, particularly on quick shifts?”

14Centre Differential Viscous Coupling Failure (GC8/GF8)

Drive slowly in a tight circle (both directions) in a carpark - a healthy viscous coupling allows slight slip without binding.petrol1992–2000TransmissionRead the full fault: symptoms, where to look, what to ask the seller

15DCCD Centre Differential Bearing Wear (GD/GG STI EJ207/EJ257)

During a test drive, cycle through the DCCD lock settings while driving straight at moderate speed and listen for changes in vibration or drone.petrol2000–2007Transmission
OccasionalTransmission $900–$3,000 to fix

Can't confirm for this car

The Driver Controlled Centre Differential (DCCD) fitted to GD/GG STI models combines mechanical and electromagnetic clutch packs with internal bearings sensitive to fluid degradation and deferred service intervals. Worn DCCD bearings produce a rumbling vibration felt through the drivetrain, most obvious on light throttle at steady speed. Failure of the electromagnetic clutch pack or bearing assembly causes the DCCD to lose differential control, leaving the centre diff stuck in full lock or free mode depending on the failure direction. Full DCCD rebuilds are expensive; regular differential fluid changes at Subaru-specified intervals can significantly extend service life and delay bearing wear.

Symptoms to notice

  • Rumbling or droning vibration through the drivetrain at light throttle cruise
  • DCCD warning light or erratic DCCD lock display
  • Vibration character that changes when cycling DCCD lock settings
  • Clunking from the centre of the car during load changes

What to check

  1. During a test drive, cycle through the DCCD lock settings while driving straight at moderate speed and listen for changes in vibration or drone.
  2. Check for any warning lights on the DCCD dashboard controller.
  3. Ask the seller for the DCCD and transfer case fluid service history.

Where to look: Centre differential unit within the gearbox/transfer case assembly, beneath the cabin floor

Parts involved: Differential.

Ask the seller

  • “Has the DCCD fluid ever been serviced? If so, when and with what fluid specification?”
  • “Has any drivetrain vibration or DCCD warning light ever been present?”
  • “Has the DCCD unit ever been repaired or rebuilt?”

16Radiator and Cooling System Neglect Leading to Overheating

Check coolant colour and condition - it should be clean, not brown or rusty.petrol1992–2014CoolingRead the full fault: symptoms, where to look, what to ask the seller

17Intercooler Charge Pipe Hose Split Under Boost

Inspect all intercooler connection hoses by squeezing them firmly — the rubber should be pliable and soft, not hard and brittle.petrol2001–2021EngineRead the full fault: symptoms, where to look, what to ask the seller

18EJ25 Excessive Oil Consumption Between Service Intervals

Check the oil dipstick level and compare it to the expected level given the stated last service date and mileage.petrol2014–2021Engine
CommonEngine $800–$4,500 to fix

Can't confirm for this car

Beyond head gasket failure, the EJ25 flat-four in WRX STI models is documented to consume engine oil at rates significantly above normal — commonly 0.5 to 1.5 litres per 1,000 km on high-mileage or hard-driven examples — due to worn valve stem seals, degraded piston rings, and the horizontally-opposed cylinder layout that pools oil on the lower bank when the engine sits unused. This issue is separate from head gasket failure and can coexist with it. Subaru of America issued guidelines acknowledging elevated oil consumption in EJ-series engines. Running low on oil in an EJ25 without realising it is a common precursor to more serious failures.

Symptoms to notice

  • Blue smoke from exhaust on cold startup that typically clears within 30–60 seconds for lower-bank pooling, but persists if seals are worn
  • Oil level dropping more than one mark on the dipstick between 3,000–5,000 km service intervals
  • Blue tinge to exhaust smoke during hard acceleration at high RPM
  • Oil fouling on spark plugs, visible on inspection as wet or oily electrode deposits
  • Smell of burning oil from the exhaust under load

What to check

Check the oil dipstick level and compare it to the expected level given the stated last service date and mileage. Blue tint to exhaust smoke on startup (from pooled oil on lower cylinders) is normal for boxer engines but should clear within 30 seconds; persistent blue smoke at idle or under acceleration indicates seal wear. Ask the seller to demonstrate the oil level on the dipstick at the time of inspection. If a workshop inspection is possible: A leak-down test identifies whether consumption is ring or valve related.

Where to look: Engine internal — valve stem seals (cylinder head), piston rings (block); lower cylinder bank oil pooling is inherent to the boxer layout

Parts involved: Head gasket.

Ask the seller

  • “How much oil does the car typically consume between scheduled oil changes, and have you had to top it up between services?”
  • “Has a leak-down test or compression test been performed, and what were the results?”

19Rear LSD Clutch-Type Differential Chatter from Fluid Degradation (GD/GG STI)

Drive slowly in full-lock circles in both directions in a car park and feel for juddering through the floor or steering wheel.petrol2000–2007Transmission
CommonTransmission $150–$650 to fix

Can't confirm for this car

The WRX STI rear limited-slip differential uses clutch packs that require specific friction-modifier fluid to operate smoothly. When the differential fluid degrades or is replaced with an incorrect specification, the clutch packs generate a juddering or chattering sensation during low-speed tight-radius turns such as car park manoeuvres or U-turns. This is primarily a maintenance failure rather than a mechanical fault, but deferred fluid changes are extremely common on NZ and AU used imports. If left without a fluid change for extended periods, the clutch pack friction material wears beyond the point where a fluid change alone can resolve the juddering.

Symptoms to notice

  • Juddering or chattering from the rear of the car during slow tight-radius turns
  • Vibration through the floor and steering wheel when parking at full lock
  • Clunking felt through the car body during low-speed cornering

What to check

Drive slowly in full-lock circles in both directions in a car park and feel for juddering through the floor or steering wheel. If juddering is present, a fluid change may resolve it; if the vibration is severe or persists after fresh fluid, internal clutch pack wear is likely requiring differential rebuild.

Where to look: Rear limited-slip differential

Parts involved: Differential, Clutch.

Ask the seller

  • “When was the rear differential fluid last changed, and with what specification fluid?”
  • “Has any juddering or chattering been noticed when turning or parking at low speed?”
  • “Was the correct LSD-specification differential fluid used at the last service?”
Electrical1

01Electric Power Steering Rack Rattle

Drive over rough surfaces at low speed and listen for rattle from the steering rack area.2014 onwardElectrical
CommonElectrical $600–$2,200 to fix

Can't confirm for this car

The EPS rack develops an internal rattle at low speeds over rough surfaces.

Symptoms to notice

  • Knocking or rattling from steering rack area at low speeds
  • Vibration through steering wheel during slow manoeuvring

What to check

Drive over rough surfaces at low speed and listen for rattle from the steering rack area.

Where to look: Electric power steering rack assembly

Parts involved: Steering rack.

Ask the seller

  • “Has the electric power steering rack rattle been inspected or repaired?”
Body, brakes, suspension & interior8

01Rear Wheel Arch and Sill Rust (JDM Imports)

Inspect rear wheel arch lips and inner seams closely - push along the inner arch seam and feel for softness indicating rust through.petrol1992–2021Body & RustRead the full fault: symptoms, where to look, what to ask the seller

02Rear Subframe Bushing Deterioration (GE/GH/GR/GV WRX and STI)

Visually inspect the rubber bushing condition for cracking, splitting, or collapse around the subframe mounting points.petrol2007–2014SuspensionRead the full fault: symptoms, where to look, what to ask the seller

03Front Strut Top Mount / Bearing Collapse

With the bonnet open, have someone turn the steering wheel lock to lock while you press down on the strut top mount and feel for play or roughness.petrol2000–2014Suspension
CommonSuspension $400–$1,100 to fix

Can't confirm for this car

GD/GG and GH/GR WRX strut top mounts and bearing plates are a known wear item that collapses prematurely compared to other vehicles of the same era. The WRX's stiffer suspension and performance use accelerates wear. Failed top mounts cause a characteristic clunking when steering from lock to lock and over bumps, and allow the strut to pivot on a seized bearing rather than rotating smoothly, causing tyre scrub, uneven wear, and vague steering response.

Symptoms to notice

  • Clunking or knocking from front suspension over bumps
  • Clunking when steering from lock to lock while stationary
  • Vague or notchy steering feel
  • Uneven front tyre wear
  • Grinding sensation through steering wheel when turning

What to check

With the bonnet open, have someone turn the steering wheel lock to lock while you press down on the strut top mount and feel for play or roughness. Bounce each front corner firmly and listen for clunking. Inspect the rubber top mount for cracking and the bearing plate for corrosion or roughness.

Where to look: Front strut top mount and bearing plate, inside the engine bay at the top of each front strut tower

Parts involved: Shock absorber / strut.

Ask the seller

  • “Has the front suspension ever been serviced or the struts replaced?”
  • “Is there any clunking over bumps or when steering?”
  • “Has the car been used on track or driven hard on rough roads?”

04Rear Wheel Bearing Premature Failure

Also try 9 and 3 o'clock positions to feel for lateral play.petrol2001–2021Suspension
CommonSuspension $350–$900 to fix

Can't confirm for this car

The rear wheel bearings on GD and GE chassis WRX and STI are a press-fit hub-and-bearing assembly that is susceptible to accelerated wear on cars that have been driven hard, autocrossed, or had wheel alignment significantly altered by lowering springs or coilover installation without correcting rear camber. High negative camber angles — common on STI models with aggressive alignment settings — place asymmetric lateral loads on the bearing races that the design does not accommodate well over high mileage. Road salt exposure in colder climates and water ingress from rally-style driving also accelerates race corrosion. The VA chassis uses a similar design and shows the same pattern on high-mileage examples. Bearing failure progression is usually audible before catastrophic but a severely worn bearing can cause brake rotor runout and ABS activation at speed.

Symptoms to notice

  • Rhythmic droning or humming noise from rear that changes with vehicle speed
  • Noise changes when load-shifting left or right during lane changes
  • Vibration felt through rear of vehicle at highway speed
  • ABS activation on straight road at speed (severe bearing runout)
  • Rear wheel has visible play when rocked at 12 and 6 o'clock positions with wheel off ground

What to check

Also try 9 and 3 o'clock positions to feel for lateral play. Spin each rear wheel by hand and listen/feel for roughness or rumbling through the hub. On a test drive, change lanes at 80+ km/h and note if the humming noise changes tone — a noise that worsens when loading the right wheel points to the right rear bearing. If a workshop inspection is possible: With the vehicle safely on jack stands, grasp each rear wheel at 12 and 6 o'clock and attempt to rock it — any detectable play indicates bearing wear.

Where to look: Rear hub assembly — wheel bearing integrated into hub carrier on both rear corners

Parts involved: Wheel bearing.

Ask the seller

  • “Have the rear wheel bearings ever been replaced?”
  • “Has the car been lowered with springs or coilovers?”
  • “What is the current wheel alignment specification, particularly rear camber?”
  • “Has the car been used for any circuit or track driving?”

05Front Lower Arm Ball Joint Wear

Inspect the boot for splitting.2014 onwardSuspension
CommonSuspension $400–$900 to fix

Can't confirm for this car

Front lower arm ball joints wear causing clunking over rough surfaces.

The front wheel of a car splayed outward with the lower control arm hanging down after a ball joint separation.Example of the part — not this vehicle

A separated lower ball joint: the control arm has dropped and the wheel has splayed out under the guard.

Elfix · CC0 · Wikimedia Commons

Symptoms to notice

  • Clunking from front suspension over rough surfaces
  • Imprecise handling feel especially when cornering

What to check

Inspect the boot for splitting. If a workshop inspection is possible: With vehicle raised, lever the lower arm and check for ball joint play.

Where to look: Front lower suspension control arms

Parts involved: Ball joint.

Ask the seller

  • “Has the front lower arm ball joint been inspected or repaired?”

06Front Wheel Bearing Failure - AWD Stress

Rock the wheel at 12 and 6 o'clock checking for play.petrol1992–2021SuspensionRead the full fault: symptoms, where to look, what to ask the seller

07Brake Caliper Guide Pin Seizure

Check for pulling under braking.2014 onwardBrakes
CommonBrakes $200–$600 to fix

Can't confirm for this car

Front brake caliper guide pins seize from corrosion causing uneven pad wear.

Symptoms to notice

  • Vehicle pulling to one side under braking
  • One disc hotter than the other after moderate use

What to check

  1. Check for pulling under braking.
  2. Feel for uneven wheel heat.
  3. Inspect guide pins.

Where to look: Front brake calipers

Parts involved: Brake disc and pads.

Ask the seller

  • “Has the brake caliper guide pin seizure been inspected or repaired?”

08Rear Multi-Link Bush Collapse

Inspect rear suspension arm bushes for cracking.2014 onwardSuspension
CommonSuspension $400–$1,200 to fix

Can't confirm for this car

Rear multi-link suspension arm bushes harden and collapse causing rear knocking and imprecision.

Symptoms to notice

  • Knocking from rear suspension over rough surfaces
  • Imprecise rear handling feel

What to check

  1. Inspect rear suspension arm bushes for cracking.
  2. Push arms — any movement indicates collapsed bushes.

Where to look: Rear multi-link suspension arm bushes

Ask the seller

  • “Has the rear multi-link bush collapse been inspected or repaired?”
Fluid leaks3

01EJ20 Turbo Oil Return Line Blockage and Turbo Seal Failure (GC/GF)

Check the underside of the turbo for oil weeping around compressor or turbine seals.petrol1994–2000Fluid LeaksRead the full fault: symptoms, where to look, what to ask the seller

02Turbocharger Oil Feed Line and Return Seal Leaks

With engine warm, inspect the turbocharger oil feed and return lines for seeping or wet oil.petrol1992–2014Fluid LeaksRead the full fault: symptoms, where to look, what to ask the seller

035-Speed Gearbox Rear Extension Housing Oil Seal Leak (GC/GF MT)

The rear output shaft seal on the GC/GF 5-speed manual transmission is a documented wear item that weeps or drips gear oil from around 100,000 km.petrol1994–2000Fluid LeaksRead the full fault: symptoms, where to look, what to ask the seller
Other Subaru STI engines and years1 documented issue that do not apply to the one you picked.
Engine, transmission & cooling1

01Lineartronic CVT TR580/TR690 Belt and Bearing Failure

During a test drive, perform a moderate full-throttle acceleration from 50 km/h to 100 km/h and feel for any slip, shudder, or hesitation.petrol2015–2021Transmission
OccasionalTransmission $5,500–$13,000 to fix

Does not apply

The VA-chassis WRX automatic uses Subaru's Lineartronic continuously variable transmission (TR580 or TR690 depending on market). The steel push-belt that transfers drive between the primary and secondary pulleys is designed for a specific torque range and thermal envelope. In WRX applications the FA20DIT produces torque peaks that stress the belt clamping force limits, and prolonged high-load driving — towing, mountain passes, repeated full-throttle acceleration — causes belt micro-slip that generates heat and progressive belt element wear. The CVT fluid degrades faster than the factory 100,000 km service interval suggests under performance use, and degraded fluid reduces clamping efficiency, accelerating belt and pulley surface wear. Secondary pulley bearings also fail on higher-mileage units. Complete transmission replacement is the typical repair as remanufactured units are expensive and rebuilds require specialist tooling.

Symptoms to notice

  • Shuddering or jerking during light throttle cruising
  • Slipping sensation — engine revs rise without corresponding vehicle acceleration
  • Whining or grinding noise from transmission under load
  • CVT warning light or transmission overheat indicator
  • Unusual fuel consumption increase
  • Delayed engagement from standstill

What to check

  1. During a test drive, perform a moderate full-throttle acceleration from 50 km/h to 100 km/h and feel for any slip, shudder, or hesitation.
  2. Inspect CVT fluid colour at the dipstick — should be pink/light red and clean; dark brown or burnt-smelling fluid indicates thermal abuse.
  3. Check service records for CVT fluid change history.
  4. Request a scan tool health check for transmission temperature and adaptation data.

Where to look: Transmission — CVT unit mounted transversely behind engine in engine bay

Parts involved: CVT belt and pulleys.

Ask the seller

  • “Has the CVT fluid ever been changed, and at what mileage?”
  • “Has the car been used for towing?”
  • “Has the transmission ever overheated or shown a warning light?”
  • “Has the car been driven consistently with sport or manual mode?”

Subaru STI faults in detail

Each of these has its own page: the symptoms, where to look, what to ask the seller and what the repair costs. Free, no account needed.

5-Speed Gearbox Rear Extension Housing Oil Seal Leak (GC/GF MT)Major · Fluid LeaksCentre Differential Viscous Coupling Failure (GC8/GF8)Major · TransmissionEJ Spun Rod Bearing from Oil StarvationCritical · EngineEJ20 Phase 1 Head Gasket Failure (GC/GF 2.0T)Critical · EngineEJ20 Turbo Oil Return Line Blockage and Turbo Seal Failure (GC/GF)Major · Fluid LeaksEJ20/EJ205 Water Pump Plastic Impeller Failure (GC/GF and GD/GG)Critical · CoolingEJ20/EJ25 Head Gasket FailureMajor · EngineEJ25 STI Head Gasket FailureCritical · EngineEJ257 Piston Ringland FailureCritical · EngineFront Wheel Bearing Failure - AWD StressMajor · SuspensionIntercooler Charge Pipe Hose Split Under BoostMajor · EngineRadiator and Cooling System Neglect Leading to OverheatingMajor · CoolingRear Subframe Bushing Deterioration (GE/GH/GR/GV WRX and STI)Major · SuspensionRear Wheel Arch and Sill Rust (JDM Imports)Major · Body & RustTurbocharger Oil Feed Line and Return Seal LeaksMajor · Fluid Leaks

What these repairs cost on other cars

Some of the Subaru STI’s documented faults are repairs other models share. Each page lists the documented NZ cost for every model it affects.

Other Subaru models

Subaru Legacy54 documented faultsSubaru Forester50 documented faultsSubaru Impreza44 documented faultsSubaru BRZ26 documented faultsSubaru XV19 documented faultsSubaru Levorg13 documented faults

Subaru STI buyer questions

Is the Subaru STI reliable?

Like any used car, it depends on the specific example and its service history. Across the 32 documented faults for the Subaru STI, the recurring problem areas are engine, transmission, and cooling. A Subaru STI with a full service history and no signs of the issues listed on this page can be a sound buy but each one needs to be checked individually before you commit.

What are the most common problems with a used Subaru STI?

We've catalogued 32 known faults for the Subaru STI, covering engine, transmission, and cooling. All 32 are written out in full on this page, with the symptoms to notice, what to inspect, and typical repair costs for each. Free to read, no account needed.

How much do repairs cost on a Subaru STI?

Most single repairs on the Subaru STI fall between $600–$2,800 at NZ independent-workshop rates. Some of the 32 documented faults cost less and a few cost considerably more, and no one car needs them all. Knowing which ones to look for before you view is what lets you negotiate the price down or walk away.

Should I get a pre-purchase inspection on a Subaru STI?

Yes. A Subaru STI inspection focused on its known weak points is the single best way to avoid an expensive mistake. KickTyres gives you a guided, model-specific inspection plus a market valuation and negotiation figure for $24.90 far less than the cost of missing one of the faults on this page.