The 2021 Expedition with the 3.5L EcoBoost is still relatively young, but early adopters are already seeing catastrophic engine failures tied to valvetrain defects and cylinder deactivation issues, plus transmission cooler failures that can grenade the 10-speed if not caught early.
Catastrophic 3.5L EcoBoost Engine Failure — Cam Phaser / Valvetrain
Occasional · high severityTypical onset: 30,000-80,000 mi
Symptoms: Cold-start rattle that won't go away after warm-up, Check engine light with cam/crank correlation codes (P0016, P0017, P0018, P0019), Loss of power, rough idle, metallic ticking from valve covers, Total engine seizure in worst cases — debris circulates and scores cylinder walls
Fix: Cam phasers alone are 12-16 hours labor, but if fragments contaminate oil passages you're looking at short block replacement or full rebuild. Ford has issued TSBs but no recall yet. Many owners report total engine replacement under warranty before 60k. Out-of-warranty this becomes a $8k-15k nightmare.
Estimated cost: $8,000-15,000
Transmission Oil Cooler Line Failure
Common · high severityTypical onset: 40,000-90,000 mi
Symptoms: Transmission fluid leaking near radiator or frame rails, Pink fluid pooling under vehicle, Harsh shifts or slipping if cooler fails internally and contaminates trans with coolant, Engine overheating if coolant loss is severe
Fix: External cooler line corrosion is 2-4 hours to replace lines and flush trans. Internal cooler failure requires radiator replacement, trans flush/filter, and often valve body work if coolant mixed in. Ford TSB 21-2227 covers some cases. Catch it early or you're replacing a 10R80 transmission.
Estimated cost: $800-3,500
10-Speed 10R80 Transmission Shudder and Harsh Shifts
Common · medium severityTypical onset: 20,000-70,000 mi
Symptoms: Shudder or vibration during light acceleration, especially 3rd-6th gear, Harsh downshifts or delayed upshifts, Hunting between gears on highway cruise, Clunk or bang when coming to a stop
Fix: Ford has multiple TSBs (21-2313, 22-2065) calling for software reflash, adaptive learning reset, and fluid replacement with Mercon ULV. Reflash + fluid service is 2-3 hours. Persistent cases may need valve body replacement (8-10 hours). Some units develop internal clutch pack wear and require rebuild or replacement.
Estimated cost: $400-6,000
Backup Camera Intermittent Failure / Black Screen
Occasional · low severitySymptoms: Camera shows black screen or 'camera unavailable' message, Intermittent display, works after restart sometimes, Grid lines disappear or image freezes, Happens more in cold weather or after car wash
Fix: Often caused by water intrusion in camera connector at rear hatch or corrosion in SYNC module grounds. Ford issued recall 21V-686 for wiring harness pinch. Typical fix is 1-2 hours for connector repair/seal or camera replacement. Dealer reflash sometimes solves software glitches.
Estimated cost: $200-800
Panoramic Sunroof Wind Noise and Water Leaks
Occasional · low severityTypical onset: 10,000-60,000 mi
Symptoms: Wind whistle or howl at highway speeds from roof area, Water dripping from headliner near A-pillars or sun visors, Sunroof panel sits slightly proud or won't close flush, Drain tubes clog and overflow into cabin
Fix: Drain tube cleaning is 1 hour. Panel adjustment or seal replacement is 2-3 hours. Ford TSB 22-2158 addresses wind noise with revised weatherstripping. Persistent leaks may need full sunroof cassette realignment or replacement (6-8 hours).
Estimated cost: $150-1,200
Engine Mount Failure (Rear Transmission Mount)
Occasional · medium severityTypical onset: 50,000-100,000 mi
Symptoms: Clunk or thud on hard acceleration or deceleration, Vibration at idle, especially in Drive with brake applied, Driveline lash — feels like slack in drivetrain, Visible separation or oil-soaked rubber on mount inspection
Fix: Rear trans mount is 2-3 hours with exhaust drop. Front engine mounts add another 3-4 hours each. Twin-turbo V6 generates a lot of torque and tears these mounts. OEM parts recommended — aftermarket tend to fail quickly.
Estimated cost: $400-1,200
Great features and towing capability, but the 3.5L EcoBoost and 10R80 combo is a ticking time bomb — only buy with extended warranty or budget $10k for eventual powertrain work.
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.