The 2010 Legacy is a solid mid-size Subaru, but the 2.5L H4 suffers from notorious head gasket failures and CVT transmission issues that can cripple an otherwise dependable platform. The 3.6L H6 avoids head gasket problems but shares CVT concerns.
Head Gasket Failure (2.5L H4 only)
Common · high severityTypical onset: 80,000-130,000 mi
Symptoms: External oil leaks at head/block interface, visible as seepage below exhaust manifolds, White smoke on startup, sweet coolant smell from exhaust, Overheating or coolant loss without visible leaks, Bubbles in coolant reservoir, rough idle when warmed up
Fix: Replace both head gaskets, machine heads flat, new timing components, coolant flush. Job requires 12-16 hours labor due to boxer engine layout—everything comes out the top. Often discover warped heads requiring surfacing or replacement.
Estimated cost: $2,200-3,500
CVT Transmission Judder and Failure
Common · high severityTypical onset: 60,000-100,000 mi
Symptoms: Shuddering or vibration during acceleration from stop, especially uphill, Hesitation or delayed response when accelerating, Whining or grinding noises from transmission, Check engine light with P0700, P0845, or CVT-specific codes
Fix: Early cases may respond to CVT fluid replacement (not a flush—drain/fill only, 4 quarts at a time, repeat 2-3x). Advanced failures require remanufactured CVT replacement at 8-10 hours labor. Subaru extended warranty to 100k miles on some units due to widespread issues.
Estimated cost: $400-600 fluid service, $4,500-6,500 replacement
Rear Wheel Bearings
Occasional · medium severityTypical onset: 70,000-110,000 mi
Symptoms: Humming or grinding noise from rear that increases with speed, Noise changes pitch in turns—louder on opposite side of turn direction, Vibration through chassis at highway speeds
Fix: Replace wheel hub assembly—bearings are not serviceable separately on this generation. 1.5-2 hours per side. Subaru bearings are known weak points; OEM or high-quality aftermarket essential.
Estimated cost: $350-500 per side
Front Lower Control Arm Bushings
Common · low severityTypical onset: 80,000-120,000 mi
Symptoms: Clunking over bumps from front suspension, Steering wander or vague on-center feel, Uneven or cupped front tire wear on inner edges, Visible cracking or tearing in rubber bushings during inspection
Fix: Replace front lower control arms complete—bushings are pressed in and labor to replace bushings alone doesn't justify savings. 2-3 hours plus alignment. Expect to do both sides together.
Estimated cost: $600-900 both sides with alignment
PCV Valve / Blow-by Issues Leading to Oil Consumption
Occasional · medium severityTypical onset: 90,000-150,000 mi
Symptoms: Excessive oil consumption—1 quart per 1,000-2,000 miles, Blue smoke on deceleration or startup, Sludge buildup in intake manifold visible at throttle body, Check engine light with lean codes (P0171/P0174) from oil in MAF sensor
Fix: Replace PCV valve, clean intake manifold and throttle body, inspect valve stem seals. If piston rings are glazed from oil burning, only solution is engine rebuild or short block replacement at 20-30 hours labor. PCV alone is 1-2 hours.
Estimated cost: $150-300 PCV service, $4,000-6,500 short block
Takata Airbag Inflator Recall
Common · high severitySymptoms: No symptoms—recall based on manufacturing defect risk, Passenger airbag inflator can rupture in deployment, sending metal fragments
Fix: NHTSA recall with 10 campaigns—must be addressed at dealer at no cost. Check VIN at Subaru recall site. Do not ignore—fatalities have occurred.
Estimated cost: $0 (dealer recall repair)
Rear Differential Fluid Leak
Occasional · low severityTypical onset: 100,000+ mi
Symptoms: Gear oil spots under rear center of vehicle, Visible seepage at rear diff pinion seal or side seals, Whining from rear differential if run low on fluid
Fix: Replace pinion seal or side axle seals depending on leak location. 1.5-2.5 hours labor. If carrier bearing is worn, full rebuild required at much higher cost.
Estimated cost: $300-500 seals only
Buy the 3.6L H6 if you can find one and verify CVT health with drain-and-inspect; avoid the 2.5L unless head gaskets are already done and documented.
AI-assisted summary drawn from NHTSA recall data, our labor-times database, and platform knowledge. Not a substitute for a pre-purchase inspection on a specific vehicle.