Problems · NHTSA complaints

2021 Hyundai Sonata problems

Owners filed 135 complaints about the 2021 Hyundai Sonata with NHTSA between Mar 2021 and Oct 2026. The most-cited component is engine (34).

Complaints
135
Filed with NHTSA
Crashes
7
Reported by owners
Fires
0
Reported by owners
Injuries
13
People reported injured
Deaths
0
Reported to NHTSA
01 —By component

Complaints by component

One complaint can cite several components
  1. Engine34
  2. Power train25
  3. Fuel/propulsion system21
  4. Electrical system18
  5. Fuel system, gasoline13
  6. Forward collision avoidance9
  7. Visibility/wiper8
  8. Structure4
  9. Air bags4
  10. Visibility4
  11. Service brakes3
  12. Lane departure3
  13. Seat belts2
  14. Seats2

Complaints are unverified owner reports to NHTSA and are not normalized for sales volume. One complaint can cite several components.

Data from NHTSA Complaints API · synced Nov 10, 2026NHTSA vehicle page
02 —Trend

When complaints were filed

Does it get worse with age? Complaints per calendar year filed
View as table
Model yearComplaints filed per calendar year
20219
202218
202322
202415
202529
202642

Mileage at failure isn’t a structured field in NHTSA complaint data, so we don’t chart it. Some owners mention it in their reports below.

03 —Owner reports

Top problems in owners’ words

Verbatim from NHTSA complaints, newest first

Engine

34 reports1 crash
“At approximately 130,000 miles, vehicle developed and internal coolant leak caused by a failed Exhaust Heat Recovery System (EHRS) in the center muffler assembly, matching TSB 23-EM-009H - a known manufacturing defect documented by Hyundai. Coolant has been slowly leaking internally into the exhaust system. The authorized Hyundai dealership initially failed to diagnose the internal leak and told me there was no leak and wanted to send me home. After pushing back, the internal leak was confirmed. If not caught, this defect could result in engine overheating or complete engine failure without warning. Hyundai Motor America has denied goodwill coverage despite this being a documented manufacturing defect.”
Owner complaint to NHTSAFiled Jun 24, 2026Engine, Fuel/propulsion systemODI 11746137

Power train

25 reports1 related recall
“My 2021 Hyundai Sonata N Line suffered a catastrophic, sudden total loss of drive power while operating at speed on a public roadway, creating an immediate crash hazard. The vehicle lost forward propulsion and the gear selector flashed a blinking 'R' when reverse was attempted. The vehicle was towed to an authorized dealer, [XXX] Hyundai Southtowne, where their factory GDS tool pulled transmission code P283601 (Shift Fork 'B' Position Circuit). This matches the exact critical safety failure path targeted by Federal Safety Recall 236 (NHTSA Campaign 22V-746) for the 8-speed wet-DCT high-pressure electric oil pump circuit failure. The vehicle previously received the 2022 software patch, but the underlying physical hardware has now actively degraded. The dealership is attempting to deny the federal safety recall remedy based on the vehicle's high mileage. An active corporate consumer affairs investigation has been opened under Case #XXX.”
Owner complaint to NHTSAFiled Sep 28, 2026Power trainODI 11767539

Fuel/propulsion system

21 reports1 crash
“DESCRIPTION OF SAFETY DEFECT & IMMEDIATE HAZARD:My 2021 Hyundai Sonata SEL is currently exhibiting the most severe, catastrophic symptoms of the fuel tank expansion defect covered under NHTSA Campaign 25V796000. The fuel tank has expanded so drastically that it physically warped the structural interior of the cabin, violently popping the rear passenger seat completely out of its assembly while the vehicle was in motion. Furthermore, there is a constant, heavy, raw gasoline odor inside and around the vehicle. The vehicle is a documented, active fire, explosion, and vapor inhalation hazard. It is currently physically located at Sterling Hyundai in Lafayette, LA.DESCRIPTION OF MANUFACTURER NON-COMPLIANCE & REFUSAL TO REMEDY:Hyundai Motor America and Sterling Hyundai are in direct violation of their legal obligation to provide a safe, accessible remedy or interim safety accommodations under federal recall guidelines. An Executive Case Manager from Hyundai Corporate has officially refused to provide a direct-billed rental vehicle or a dealer loaner.Initially, a third-party rental vehicle was provided. However, that vehicle was compromised in an accident and wrecked…”
Owner complaint to NHTSAFiled Sep 23, 2026Fuel/propulsion systemODI 11766388

Electrical system

18 reports
“The left turn signal works intermittently. It has now stopped working about 90% of the time. The multi-function switch was replaced 3 times and I am still having the issue. The signal won't work on the exterior and it won't light up on the interior dash either. This is creating an unsafe driving environment which increases crash rates. Multiple vehicle owner with the same make/model/year are experiencing this issue, which I have found during research.”
Owner complaint to NHTSAFiled Oct 23, 2026Electrical systemODI 11773269

Fuel system, gasoline

13 reports2 related recalls
“The contact owns a 2021 Hyundai Sonata. The contact received notification of NHTSA Campaign: 25V796000 (Fuel System, Gasoline); however, parts were on back order. The contact stated that while driving at an undisclosed speed, the vehicle jerked with an abnormal gasoline odor inside the vehicle. An unknown warning light was temporarily illuminated. Upon further inspection, the contact became aware that the fuel level had dropped. The vehicle was taken to a local dealer where it was diagnosed with an expanded fuel tank. The contact stated that the O2 sensor, spark plugs, and ignition coils were replaced by a local independent mechanic; however, the failures persisted. The contact had headaches while driving the vehicle. Medical attention was not needed. The manufacturer was made aware of the failure. The failure mileage was approximately 100,000.”
Owner complaint to NHTSAFiled Sep 17, 2026Fuel system, gasolineODI 11765048

Forward collision avoidance

9 reports2 crashes
“Will be driving the car and suddenly hear a beep. Then the dashboard will flash with the ABS light engine light tire pressure light check Blindspot sensors, forward collision sensors. once all the lights appear on the dashboard, I can no longer accelerate. i’ve cleaned the throttlebody. I’ve replaced the gas pedal and it’s still kicking back the same code it still does it the same identical thing. It’s given out on me three times since December with an infant in the car. We are now in February.”
Owner complaint to NHTSAFiled Feb 1, 2026Unknown or other, Lane departure, Forward collision avoidanceODI 11714874
Data from NHTSA Complaints API (owner reports, unverified) · synced Nov 10, 2026

Complaints are unverified owner reports to NHTSA and are not normalized for sales volume. One complaint can cite several components.