AI Damage2021 Hyundai Sonata: common problems
Owners of the 2021 Hyundai Sonata filed 134 complaints with NHTSA, most often about engine and powertrain. The maker issued 90 service bulletins for this year. Details by component below, with sources.
Key figures
- Owner complaints
- 134
- involving a crash
- 7
- Technical service bulletins (TSB)
- 90
What fails most often
- 1 Engine 25% of all complaints
- 2 Powertrain 19% of all complaints
- 3 Fuel/propulsion system 16% of all complaints
- 4 Electrical system 13% of all complaints
- 5 Fuel system 10% of all complaints
- 6 Visibility 9% of all complaints
- 7 Forward collision avoidance 7% of all complaints
- 8 Structure 3% of all complaints
- Engine: 34 complaints (25% of all), 1 of them with a crash reported by the owner; manufacturer bulletins for this component: 6.
- Powertrain: 25 complaints (19% of all); manufacturer bulletins for this component: 27.
- Fuel/propulsion system: 21 complaints (16% of all), 1 of them with a crash reported by the owner; manufacturer bulletins for this component: 6.
- Electrical system: 17 complaints (13% of all); manufacturer bulletins for this component: 18.
- Fuel system: 13 complaints (10% of all).
Engines and transmissions
US-market versions per EPA. On the right: how many NHTSA complaints name this engine or transmission type.
- 1.6 L · petrol · turbo · 4 cyl
- 2.5 L · petrol · 4 cylnamed in 2 complaints
- 2.5 L · petrol · turbo · 4 cylnamed in 2 complaints
- 2 L · hybrid · 4 cyl
- automatic, 8-speed
- dual-clutch (DCT), 6-speednamed in 4 complaints
- dual-clutch (DCT), 8-speednamed in 4 complaints
Drive: FWD
Symptoms owners describe
How many of the 134 NHTSA complaints mention each symptom (automatic count from complaint text; one complaint can mention several).
Components owners complain about
| Component | Owner complaints | involving a crash | Technical service bulletins (TSB) |
|---|---|---|---|
| Engine | 34 | 1 | 6 |
| Powertrain | 25 | 0 | 27 |
| Fuel/propulsion system | 21 | 1 | 6 |
| Electrical system | 17 | 0 | 18 |
| Fuel system | 13 | 0 | 0 |
| Visibility | 12 | 0 | 3 |
| Forward collision avoidance | 9 | 2 | 2 |
| Structure | 4 | 0 | 3 |
| Air bags | 4 | 2 | 2 |
| Service brakes | 3 | 1 | 2 |
| Lane departure | 3 | 0 | 1 |
| Steering | 2 | 0 | 4 |
| Seat belts | 2 | 0 | 0 |
| Seats | 2 | 0 | 0 |
What owners report
Short excerpts of NHTSA complaints in the original wording. These are owner statements not verified by NHTSA; personal data removed.
During a front end collision the car did not auto brake and the air bags did not deploy. The car has been totaled and is currently at a dealership for insurance appraisal.
During a routine maintenance appointment at the dealership (Vancouver Hyundai 6802 NE 40th Street, Vancouver [ZIP]) they identified a catastrophic engine failure due to internal component deterioration and the engine needs to be replaced.
Vehicle in front of me stopped. Six car lengths between us. I applied brakes, nothing, I even put my left foot on top of my right foot. There was plenty of time to stop but brake peddle wouldn’t go down, Felt like it was locked. Automatic Brake Sensor didn’t work either.
The car only suffered cosmetic damage thankfully, but the air bags did not deploy. I have since then found out that the front air bag crash sensors are in a spot where they are practically useless unless you hit something pretty high up and destroy the headlights in the process.
During the incident, no injuries were reported, and no police report was filed. The vehicle was taken to the local dealer who was unable the duplicate the failure. The manufacturer was also notified of the failure. The approximate failure mileage was 1,400.
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…
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 issue is that at a cold start, the car makes a popping sound, jerks and shakes. The car hesitates to accelerate. You can hear the noise of acceleration but RPM does not go past 3 and MPH doesn't go past 30mph. I'm unable to upload docs because of the upload limit.
When owners complained
NHTSA complaints by filing year. The peak shows at what age the problems show up most.
Comparison
By complaint count this model year ranks 470 of 2,102 model years in the NHTSA data (top 22% most complained about).
On average one model year of the Sonata has 236 complaints (11 years in the data). This year has 134, below average.
What to check before buying
- Engine. Cold start, unusual noises, oil leaks and engine codes.
- Powertrain. Shift quality under load, harsh shifts, transmission codes, CV joints.
- Fuel/propulsion system. Fuel smell, leaks, rough running, fuel-system codes.
- Electrical system. Scan all modules, test the battery and alternator, inspect connectors near the impact zone.
Manufacturer service bulletins
Bulletin titles as filed with NHTSA.
- Some vehicles equipped with internal combustion engines may exhibit higher-than-expected engine oil…
Some vehicles equipped with internal combustion engines may exhibit higher-than-expected engine oil consumption. This bulletin outlines the combustion chamber cleaning procedure for vehicles diagnosed with this…
- Certain vehicles equipped with internal combustion engines may exhibit higher-than-expected engine oil…
Certain vehicles equipped with internal combustion engines may exhibit higher-than-expected engine oil consumption. This bulletin provides the inspection and repair procedures for vehicles exhibiting this condition…
- This bulletin provides information related to a Transmission Control Unit (TCU) software update for some…
This bulletin provides information related to a Transmission Control Unit (TCU) software update for some vehicles equipped with an 8-speed wet dual clutch transmission (8WDCT). The software update revises the touch…
- The National Highway Traffic Safety Administration (NHTSA) has identified the presence of substandard and…
The National Highway Traffic Safety Administration (NHTSA) has identified the presence of substandard and dangerous driver’s-side airbag inflators manufactured by Jilin Province Detiannuo Automobile Safety System Co…
- The National Highway Traffic Safety Administration (NHTSA) has issued an urgent safety advisory regarding…
The National Highway Traffic Safety Administration (NHTSA) has issued an urgent safety advisory regarding dangerous, counterfeit driver‑side airbag inflators manufactured by Jilin Province Detiannuo Automobile Safety…
- Some vehicles may exhibit difficulty starting in cold weather
This bulletin provides the procedure to perform an inspection on the starter magnetic switch for potential freezing and, if necessary, replace the starter magnetic switch (solenoid) assembly.
- Some Santa Cruz (NXT), Santa Fe (TMA, MX5A), and Sonata (DN8A) models may require replacement of the…
Some Santa Cruz (NXT), Santa Fe (TMA, MX5A), and Sonata (DN8A) models may require replacement of the 8-speed wet dual clutch transmission (8WDCT) when the vehicle sets one of the high pressure electric oil pump (HP…
- Some 2019MY and newer vehicles equipped with a front view camera may illuminate certain warning lights and…
Some 2019MY and newer vehicles equipped with a front view camera may illuminate certain warning lights and trigger DTC C272246 fault code for the front camera. In the following cases, the front camera auto-calibration…
- Some Sonata (DN8, DN8A) vehicles may have DTCs P218100, P2181F0, and/or P2181F1 (Cooling System…
Some Sonata (DN8, DN8A) vehicles may have DTCs P218100, P2181F0, and/or P2181F1 (Cooling System Performance) set in the Engine Control Module, resulting in an illuminated Check Engine warning lamp. Follow the procedure…
- Some vehicles equipped with a 2.5L GDI Theta III engine (non-Turbo) may exhibit one or more misfire DTCs…
Some vehicles equipped with a 2.5L GDI Theta III engine (non-Turbo) may exhibit one or more misfire DTCs due to the GDI fuel injectors leaking internally. This may be caused by internal filter breakage in the injector…
- This bulletin provides information regarding condensation related to the accumulated moisture in the…
This bulletin provides information regarding condensation related to the accumulated moisture in the headlamp, rear combination lamp, daytime running lamp (DRL), or fog lamp. This TSB illustrates the various causes of…
- This bulletin provides information related to the changes introduced in the 2025 1st Navigation Map and…
This bulletin provides information related to the changes introduced in the 2025 1st Navigation Map and Software Update. The changes may vary depending on vehicle type, model, and navigation system as described in this…
NHTSA lists 90 bulletins for this year; the 12 newest are shown here.
Other years of this model
Questions and answers
What are the most common problems with the 2021 Hyundai Sonata?
Owner complaints to NHTSA most often mention: engine, powertrain, fuel/propulsion system. Total complaints: 134. The most frequent symptoms in complaint texts: warning lights, check engine (20%), windows, sunroof (10%), loss of power / limp mode (9%).
How many service bulletins (TSB) were issued for the 2021 Hyundai Sonata?
NHTSA lists 90 manufacturer service bulletins for this year. A bulletin tells dealers how to diagnose or fix a known issue; it is not a recall.
Should I buy a 2021 Hyundai Sonata from a US auction?
Owner complaints describe defects, not crash damage. Before bidding, check the components listed above and review the lot photos: VinWind builds a report of visible and hidden damage by VIN.
Other 2021 models
Read also
Sources: public NHTSA data (USA): service bulletins and owner complaints; YouTube: links to videos credited to their authors. Complaints are owner statements not verified by NHTSA, and describe defects rather than crash damage. Data updated 2026-11-04.