The 2018 G90 with the 3.3T engine is a luxurious sedan that suffers from a catastrophic engine defect: metal debris in the crankshaft can cause bearing failure and total engine destruction, often with little warning. Otherwise well-built, but this single issue dominates the ownership experience.
Theta II Engine Bearing Failure / Sudden Engine Seizure
Common · high severityTypical onset: 40,000-90,000 mi
Symptoms: Metallic knocking or ticking from engine bay, especially cold start, Metal shavings in oil during changes, Check engine light with rod bearing codes (P1326), Sudden loss of power or complete engine seizure while driving, Oil pressure warning light
Fix: The 3.3T shares architecture with Hyundai's problematic Theta II family. Manufacturing defects left metal debris in crankshaft oil passages, starving rod and main bearings. Only real fix is complete engine replacement or short block swap. 18-25 labor hours for R&R, plus teardown/diagnosis time. Many dealers replace under extended warranty (Hyundai settlement covers some), but out-of-pocket owners face catastrophic costs.
Estimated cost: $8,000-15,000
Turbocharger Wastegate Rattle and Failure
Occasional · medium severityTypical onset: 60,000-100,000 mi
Symptoms: Rattling noise on cold start that fades after warmup, Loss of boost pressure or sluggish acceleration, Check engine light with underboost codes (P0299, P0234), Excessive oil consumption, Blue smoke on acceleration
Fix: Wastegate actuator rods wear or the wastegate flapper itself loosens, causing rattle and boost control issues. Eventually turbos fail outright. Each turbo replacement is 6-8 hours labor. Both turbos often fail within 10k miles of each other, so some shops recommend doing both. NHTSA recall 20V-817 covered some early failures, but many fall outside recall window.
Estimated cost: $2,200-3,500 per turbo
Transmission Oil Cooler Line Leaks
Occasional · medium severityTypical onset: 50,000-80,000 mi
Symptoms: Transmission fluid puddles under vehicle (red fluid), Burnt transmission fluid smell, Harsh shifting or slipping when fluid gets low, Transmission overheating warnings on instrument cluster
Fix: External cooler lines crack at crimp points or the cooler itself develops pinhole leaks. Simple line replacement is 2-3 hours, but often the external cooler housing needs replacement too. Must flush system and refill with correct SP-IV RR fluid. Catch it early before low fluid damages clutch packs.
Estimated cost: $600-1,200
Starter Motor Solenoid Failure (No-Crank)
Occasional · high severitySymptoms: Single click when turning key, but engine won't crank, Intermittent no-start that becomes permanent, All electrical systems work, battery tests good, No grinding, just dead silence or single click
Fix: Solenoid contacts burn out prematurely. NHTSA recall 21V-481 covered 2017-2019 G90s, so check if already performed. If not recalled, starter replacement is straightforward: 1.5-2.5 hours depending on access. V6 has better access than V8. Hyundai should cover this under recall even if not notified.
Estimated cost: $400-700 (or $0 if recall applies)
Windshield Stress Cracks and Wiper Motor Failures
Occasional · low severitySymptoms: Horizontal crack appearing from lower windshield edge without impact, Wipers moving slowly or stopping mid-cycle, Wiper park position inconsistent, Burning smell from wiper motor area
Fix: Windshields crack spontaneously from frame stress (recall 19V-023 for delaminated glass). Wiper motors also fail due to binding linkage putting excess load on motor. Windshield replacement is insurance work typically. Wiper motor is 1.5 hours. Check if recall work was completed on any used example.
Estimated cost: $350-600 for wiper motor; windshield varies by insurance
Exhaust Manifold Cracking and Heat Shield Rattles
Rare · medium severityTypical onset: 70,000-120,000 mi
Symptoms: Ticking noise that increases with RPM, Exhaust smell in cabin, Check engine light with oxygen sensor codes (P0420, P0430), Visible soot around manifold/turbo connection, Heat shield rattle on cold start
Fix: Twin-turbo setup runs manifolds extremely hot; cracks develop at merge collectors or turbo flanges. Recall 20V-817 addressed some manifold issues but not all. Heat shields also rust and break loose. Manifold replacement per side: 5-7 hours. Often done during turbo replacement since access is similar.
Estimated cost: $1,800-3,200 per side
Only buy if recalls completed, service records pristine, AND you have warranty coverage — the engine time bomb makes this otherwise excellent luxury sedan a gamble without protection.
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.