The 2021 Santa Fe is mostly solid but has significant engine reliability concerns on certain powertrain combinations, plus transmission cooling issues that can cascade into expensive repairs if ignored. The 2.5L turbo and base 2.5L have the most documented problems.
Catastrophic Engine Failure - Theta II 2.5L Turbo
Occasional · high severityTypical onset: 30,000-80,000 mi
Symptoms: metal shavings in oil, knocking sounds from bottom end, sudden loss of oil pressure, check engine light with bearing-related codes, complete engine seizure
Fix: Rod bearings fail prematurely due to debris from manufacturing process not fully cleared in earlier Theta engines. Requires complete engine replacement or full rebuild with new short block. 18-25 labor hours depending on AWD vs FWD. Many customers qualify for extended warranty coverage under settlement, but out-of-pocket is brutal.
Estimated cost: $8,000-12,000
Transmission Oil Cooler Failure
Common · high severityTypical onset: 40,000-90,000 mi
Symptoms: transmission fluid mixing with coolant (strawberry milkshake in reservoir), transmission slipping or harsh shifts, overheating transmission, coolant loss with no external leaks
Fix: Internal cooler inside radiator fails, cross-contaminating fluids. Requires radiator replacement, complete transmission flush (sometimes multiple flushes), new transmission fluid and filter. If caught late, transmission rebuild needed. This is THE failure mode to watch. 6-8 hours for cooler/flush, add 15-20 if trans is damaged.
Estimated cost: $1,200-2,500 (cooler only), $4,500-7,000 (with trans damage)
Fuel Line Connector Leaks
Occasional · high severitySymptoms: strong fuel smell, visible fuel puddles under vehicle, fuel gauge drops faster than normal, check engine light for evaporative system
Fix: Recall-documented issue where fuel feed hose connector can crack or separate. Fire risk makes this urgent. Hyundai has issued recalls (check VIN), but pre-recall or out-of-coverage repairs involve fuel line assembly replacement. 2-3 hours labor.
Estimated cost: $400-800 (if not recall-covered)
Backup Camera Failures
Occasional · low severityTypical onset: 20,000-60,000 mi
Symptoms: intermittent black screen when shifting to reverse, distorted or flickering camera image, camera works only when cold/hot, complete camera failure
Fix: Water intrusion or connector corrosion at tailgate camera. Sometimes covered under recall, sometimes not. Requires camera replacement and occasionally tailgate wiring harness repair. 1.5-2 hours.
Estimated cost: $350-650
Transmission Mounts Premature Wear
Common · medium severityTypical onset: 50,000-90,000 mi
Symptoms: clunking when shifting from park to drive, excessive vibration at idle, lurching feeling during acceleration, visible sagging of transmission when inspected
Fix: Hydraulic transmission mount fails earlier than expected, especially on turbo models with more torque. Replacement is straightforward but requires supporting powertrain. 2-3 hours.
Estimated cost: $400-700
Windshield Stress Cracks
Occasional · low severitySymptoms: cracks originating from upper edge near mirror mount with no impact point, cracks starting at A-pillar area, rapid crack propagation in cold weather
Fix: Stress cracks from manufacturing or bonding issues, covered under recall for some VINs. Windshield replacement with recalibration of forward collision systems. 3-4 hours including ADAS calibration.
Estimated cost: $800-1,400 (with ADAS recalibration)
Buy the 3.5L V6 or skip it — the turbo four-cylinders carry too much catastrophic engine risk for a 2021, and transmission cooler failures are common enough to make this a gamble without warranty coverage.
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.