The 2023 Forester with the FB25 2.5L boxer engine represents Subaru's mature fifth-generation platform. While generally reliable, it shares some long-standing Subaru weaknesses including CVT fluid cooling issues and the boxer engine's vulnerability to oil consumption and internal wear when maintenance lapses.
CVT Transmission Oil Cooler Failure
Occasional · high severityTypical onset: 60,000-90,000 mi
Symptoms: Transmission overheating warning light, Slipping or shuddering during acceleration, Burnt transmission fluid smell, Loss of power in hot weather or towing
Fix: Replace external oil cooler and flush CVT fluid. Requires dropping front subframe for access. 4-6 hours labor. Critical to catch early before CVT internals cook.
Estimated cost: $1,200-2,000
Excessive Oil Consumption / Piston Ring Wear
Occasional · high severityTypical onset: 80,000-120,000 mi
Symptoms: Burning through 1+ quart of oil between changes, Blue smoke on startup or acceleration, Check engine light with lean fuel codes, Failed emissions test due to oil burning
Fix: FB25 engines develop ring land carbon buildup leading to oil control ring failure. Fix requires short block replacement or full engine rebuild. 18-24 hours labor for short block swap.
Estimated cost: $4,500-7,500
Head Gasket Seepage
Rare · medium severityTypical onset: 100,000+ mi
Symptoms: External coolant or oil seepage at cylinder head mating surface, Sweet coolant smell after driving, Slow coolant loss without visible leaks, Oil spots on driveway from head gasket weep
Fix: The FB25 is much better than older EJ engines but can still develop external seepage. Both head gaskets replacement: 12-16 hours labor. Do timing components and water pump while in there.
Estimated cost: $2,800-4,200
Transmission Mount Failure
Common · low severityTypical onset: 50,000-80,000 mi
Symptoms: Clunking when shifting from Park to Drive, Excessive vibration at idle, Transmission appears to move excessively during acceleration, Knocking sound over bumps from engine bay
Fix: Rear transmission mount deteriorates from heat and CVT weight. Straightforward replacement, 1.5-2 hours labor. Replace all engine mounts if one fails.
Estimated cost: $300-500
Driveshaft Center Support Bearing Failure
Occasional · medium severityTypical onset: 70,000-110,000 mi
Symptoms: Vibration that increases with speed, worst at 40-50 mph, Clunking from underneath when accelerating or decelerating, Rumbling noise from center of vehicle, Vibration worse under load going uphill
Fix: Center support bearing on two-piece driveshaft wears out. Related to NHTSA recall for some units. Replace entire driveshaft assembly or just bearing carrier. 2-3 hours labor.
Estimated cost: $600-1,100
Fuel Filter Clogging (Direct Injection Carbon)
Occasional · medium severityTypical onset: 60,000-100,000 mi
Symptoms: Hard starting when engine is hot, Rough idle and hesitation, Loss of power under acceleration, Check engine light with fuel system codes
Fix: In-tank fuel filter and pump assembly can clog from poor fuel quality or running low on gas frequently. Requires dropping fuel tank. 3-4 hours labor. Also consider intake valve carbon cleaning at this mileage.
Estimated cost: $800-1,400
Buy it if maintenance history is documented and oil consumption is monitored, but budget for eventual CVT cooler and potential engine work past 100k — the drivetrain is the Achilles heel.
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.