The 2015 Expedition actually runs the 3.5L EcoBoost V6 (not the 5.4L Triton, which ended in 2014), and it's a solid platform overall, but turbocharged direct-injection engines bring their own quirks. Watch for carbon buildup, transmission cooler leaks, and cam phaser issues as these trucks age past 80k miles.
Transmission Oil Cooler Line Leaks
Common · medium severityTypical onset: 60,000-100,000 mi
Symptoms: Transmission fluid spots under vehicle, typically on driver's side, Low transmission fluid warning light, Burnt transmission fluid smell, Harsh or delayed shifts if fluid level drops significantly
Fix: Replace transmission cooler lines where they connect to the radiator or at quick-disconnect fittings. Ford revised these lines multiple times due to corrosion and fitting failures. 2-3 hours labor, requires lift access and proper fluid flush/refill.
Estimated cost: $400-700
EcoBoost Cam Phaser Rattle and Timing Chain Stretch
Occasional · high severityTypical onset: 80,000-140,000 mi
Symptoms: Cold-start rattle lasting 3-10 seconds, sounds like marbles in a can, Check engine light with P0016, P0017, P0018 timing correlation codes, Rough idle or hesitation on acceleration, Rattle may worsen with neglected oil changes or low oil level
Fix: Replace both cam phasers, timing chains, guides, and tensioners. This is an engine-out or cab-removal job on many examples due to tight underhood packaging. Requires special Ford tools for timing setup. 16-24 hours labor depending on shop method.
Estimated cost: $3,500-6,000
Carbon Buildup on Intake Valves (Direct Injection)
Common · medium severityTypical onset: 70,000-120,000 mi
Symptoms: Rough idle, especially when cold, Loss of power and throttle response, Misfires under load (P0300-P0306 codes), Poor fuel economy, hesitation during acceleration
Fix: Walnut-blast cleaning of intake valves, requires intake manifold removal and specialized media-blasting equipment. Some shops use chemical soak methods with mixed results. 4-6 hours labor. Preventive: catch-can installation helps long-term.
Estimated cost: $600-1,200
Turbocharger Wastegate Actuator Failure
Occasional · medium severityTypical onset: 90,000-150,000 mi
Symptoms: Check engine light with P0299 (underboost) or P0234 (overboost), Lack of power, sluggish acceleration, Turbo whine or rattling noise under boost, Limp mode activation in severe cases
Fix: Replace wastegate actuator or entire turbocharger if shaft play is excessive. Often both turbos show wear simultaneously. 6-10 hours labor for both turbos, requires removal of exhaust components and various underhood accessories.
Estimated cost: $1,800-3,500
PTU (Power Transfer Unit) Fluid Neglect and Seal Leaks
Common · medium severityTypical onset: 50,000-100,000 mi
Symptoms: Clunking or grinding from front differential area during turns, Fluid leaks visible at PTU case seams or output shaft, Whining noise proportional to vehicle speed, 4WD system malfunction messages
Fix: PTU fluid is lifetime-fill per Ford, but should be changed every 30-50k miles in real-world use. Seal replacement requires PTU removal. If noise is present, internal damage likely means full PTU replacement. 3-5 hours labor for seals, 4-6 hours for full unit swap.
Estimated cost: $500-1,000 for seals and fluid; $1,500-2,500 for PTU replacement
Rear HVAC Blower Motor Failure
Occasional · low severitySymptoms: Rear climate control blower stops working (front still functions), Squealing or grinding noise from behind rear quarter trim panels, Intermittent operation, works only on high speed, Burning smell from rear HVAC vents
Fix: Replace rear blower motor assembly, accessible from rear cargo area trim panel removal. Common on models with dual-zone rear climate. 1.5-2.5 hours labor. Ford issued TSB and recall for related issues.
Estimated cost: $300-600
Water Pump Weep Hole Leaks (EcoBoost-Specific Design)
Occasional · medium severityTypical onset: 70,000-120,000 mi
Symptoms: Coolant drips visible below water pump area, Coolant smell in engine bay, Low coolant warning light, Overheating if leak progresses unchecked
Fix: Replace water pump and thermostat housing assembly. EcoBoost uses an internal water pump driven by timing chain, so this overlaps with timing service. If caught early, can be done without full timing job. 4-8 hours labor depending on whether timing components need service.
Estimated cost: $800-1,800
Solid family hauler if maintained aggressively, but the EcoBoost complexity means higher DIY difficulty and repair costs than the old 5.4L—budget $1,500/year for deferred maintenance surprises after 100k miles.
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.