The 2015-2024 Subaru Forester with the 2.5L naturally aspirated H4 is generally reliable transportation, but the FB25 engine has well-documented weak points including oil consumption, head gasket seepage, and PCV valve failures. The CVT transmission shows occasional cooler line and mount issues but is less problematic than earlier generations.
Excessive Oil Consumption / Piston Ring Failure (FB25 Engine)
Common · high severityTypical onset: 60,000-100,000 mi
Symptoms: burning 1+ quart oil every 1,000-1,500 miles, blue smoke on cold start or under load, check engine light P0420 (catalyst efficiency) from oil fouling, frequent low oil warnings
Fix: Subaru extended warranty covered many early cases, but out-of-warranty requires short block replacement or full engine rebuild with updated piston rings. 12-16 hours labor for short block swap in-chassis. Some owners live with it and top off oil religiously.
Estimated cost: $4,500-7,500
CVT Transmission Oil Cooler Line Leaks
Occasional · medium severityTypical onset: 80,000-120,000 mi
Symptoms: red transmission fluid dripping near front of engine, low CVT fluid warning, burnt smell after highway driving, transmission temperature gauge climbing
Fix: Rubber o-rings in the cooler line connections harden and leak. Replace both cooler lines and o-rings preventively; 2-3 hours labor. Flush and refill CVT fluid while you're in there.
Estimated cost: $600-1,200
Head Gasket Seepage (External Oil Leaks)
Occasional · medium severityTypical onset: 100,000-150,000 mi
Symptoms: oil weeping from lower sides of engine block, oil smell from exhaust manifold heat, visible crusty brown residue on head/block joint, no overheating or coolant mixing—just external oil
Fix: FB25 doesn't have the catastrophic internal coolant-mixing head gasket failures of older EJ engines, but external oil seepage still happens. Both head gaskets, valve cover gaskets, and timing components while open: 14-18 hours labor.
Estimated cost: $2,800-4,500
PCV Valve Failure / Crankcase Pressure Issues
Common · low severityTypical onset: 70,000-110,000 mi
Symptoms: rough idle, oil leaking from valve cover or dipstick tube, whistling noise from engine bay, check engine light P0171/P0172 (fuel trim codes)
Fix: PCV valve integrated into valve cover; cannot replace separately on many FB25 variants—requires entire valve cover assembly. 2-3 hours per side if both are done. Clean intake valves while intake manifold is off.
Estimated cost: $800-1,400
Transmission Mount Failure
Occasional · low severityTypical onset: 80,000-130,000 mi
Symptoms: clunk when shifting from park to drive or reverse, excessive vibration at idle in gear, visible cracking or separation in rubber mount, driveline shudder on acceleration
Fix: Rear transmission mount (pitch stopper) wears from CVT torque fluctuations. Replace mount and inspect front engine mounts at same time. 1.5-2 hours labor.
Estimated cost: $300-600
Fuel Pump Failures / No-Start Condition
Rare · high severitySymptoms: intermittent no-start with crank but no fire, fuel pump not priming (no hum when key turned on), stalling at operating temperature, check engine light P0087 (fuel rail pressure low)
Fix: Some 2019-2021 models had recall for fuel pump impeller. Even post-recall, occasional pump failures occur. Drop fuel tank, replace pump assembly. 3-4 hours labor.
Estimated cost: $800-1,400
Solid choice if you verify oil consumption history and CVT maintenance records—avoid high-mileage examples with no proof of CVT services or engines burning oil.
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.