2021 Hyundai Sonata Problems
Compared with other Hyundai Sonata years
Fewer complaints than typical for this model
28/100 0.6× a typical year · 50 = typical
- Complaint rate is 0.6× that of a typical Hyundai Sonata year, weighted for crashes, fires, injuries, recalls and mileage, and allowing for the era and for how long each year has had to collect complaints.
- 49 of its 135 complaints were filed by the end of 2023.
- Most reported problem: Loss of power and fail-safe mode while driving (29 complaints, median 28,000 mi).
- 4 recall campaigns on record. A VIN search at nhtsa.gov/recalls shows open recalls for a specific vehicle.
Based only on NHTSA complaints, recalls and investigations. Not adjusted for how many vehicles were sold, and not a reliability rating. How this is calculated
- Complaints
- 135filed with NHTSA
- Median mileage
- 41,000miles, 25 complaints with mileage
- Recalls
- 4campaigns on record
- Trend
- RisingComplaints filed in the last 3 full calendar years are at least 25% higher than in the 3 years before.
- NHTSA crash rating
- 5 / 5stars overall
- EPA fuel economy
- 31 mpgcombined, 2.5L 4-cyl FWD · 27 city / 37 hwy
Sources: NHTSA records for the 2021 Hyundai Sonata (complaints, recalls, investigations), NHTSA crash tests, EPA fuel economy. Report an error
What owners report
Owners of the 2021 Sonata most often describe fuel-system problems, especially a swollen fuel tank tied to recall 25V796000, and loss-of-power events where the car drops into a limited-mobility mode or shuts off while driving. Engine complaints often involve coolant loss, misfires or oil-related stalling, while transmission complaints center on jerking, delayed engagement and no-drive conditions. Reports span low-mileage cars under 15,000 miles to vehicles past 100,000 miles.
- Fuel system
Fuel tank swelling and strong fuel odor
- 20 complaints (15%)
- median 75,242 mi at 5.2 yrs old (8 state mileage, few)
- 2 mention a crash, fire or injury
- filed 2022–2026
Complaints describe a fuel tank that expands, in some cases deforming the area around the rear seat, along with a strong gasoline smell inside the cabin and garage. Owners report the fuel gauge reading wrong, difficulty refueling, and the vehicle stalling or jerking at speed. Several say the dealer confirmed an expanded tank but that recall parts were on back order, and some report the check valve being replaced without the swelling stopping. Reported from roughly 50,000 to 140,000 miles, often after owners received the fuel-tank recall notice.
Recall 25V796000Recall 21V5240002 related service bulletins
What to check: Ask whether the check-valve recall work has been completed and whether the fuel tank has been inspected for swelling. Before buying, fill the tank and check for a fuel smell around the rear seat and in the cabin.
2 excerpts from owner complaints in NHTSA records
“I took my vehicle in for the safety recall due to an expanding fuel tank on 08/03/2026. I received my vehicle back on 8/12/2026. Hyundai performed an improper repair on the vehicle that will not correct the fuel tank expansion. They replaced the same check valve that was replaced last time I brought the vehicle in for recall on 11/20/2024 repair order # 107221 at Jones Hyundai of Belair. This valve did not and will not correct the fuel tank expansion issue. …”
NHTSA complaint #11757244, filed 2026-08“The contact owns a 2021 Hyundai Sonata. The contact received notification of NHTSA Campaign Number: 25V796000 (FUEL SYSTEM, GASOLINE); however, the part to do the recall repair was unavailable. The local dealer was contacted, and it was confirmed that the part was not yet available. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. The manufacturer was made aware of the issue. …”
NHTSA complaint #11753027, filed 2026-07, 80,484 miles - Transmission and drivetrain
Loss of power and fail-safe mode while driving
- 29 complaints (21%)
- median 28,000 mi at 2.8 yrs old (9 state mileage, few)
- filed 2021–2026
Owners describe the car losing drive power at speed, sometimes with the accelerator unresponsive and the vehicle dropping into a limited-mobility mode; some say the gear selector showed a flashing indicator. A few report jerking and popping on cold starts, or the car not moving past a low speed with the engine revving. Dealers replaced transmissions or updated control software in some cases, while others could not duplicate the problem or said the car was operating as designed. Mostly reported between about 12,000 and 92,000 miles, with several owners noting it on cold starts or during acceleration.
Recall 22V7460004 related service bulletins
What to check: Ask for the service history for transmission software updates or replacement, and whether the transmission oil pump recall was performed. Test drive from a cold start and check for jerking, delayed engagement or a flashing gear indicator.
2 excerpts from owner complaints in NHTSA records
“Car transmission seemed to make a clunking sound when selecting gear from park. The car would not accelerate, the throttle seemed to be stuck and the transmission would try to downshift, but the car was not picking up speed. I eventually pulled off the road into a parking lot and turned the car off. I then restarted the car and it seemed to clear the problem, but no warning lights ever came on, and no error codes were displayed on the instrument cluster.”
NHTSA complaint #11495865, filed 2022-12“The issue is well known across the DN8 platform, hundreds if not thousands of people have this problem.Car and driver even did an article on a car with this same 2.5L turbo DCT engine having the same problem! The problem is the ITMS or thermostat housing unit. I first experienced this getting on to a highway, I lost all acceleration, the turbo dropped to 0 pSI and I received an engine overheating warning on the dash. After pulling over the car resumed normal driving, but with oil temps running 30-40 degrees higher than normal. …”
NHTSA complaint #11526848, filed 2023-06 - Engine
Engine stalling, knocking and oil loss
- 18 complaints (13%)
- median 44,000 mi at 3.0 yrs old (5 state mileage, few)
- filed 2021–2026
Complaints describe the engine shutting off while driving or on a highway ramp, sometimes not restarting, and in a few cases being found with no oil and seized. Owners also report knocking noises, hesitation on acceleration, misfires traced to leaking fuel injectors, and, in some cars, a complete engine replacement under warranty. Dealers variously replaced injectors or engines, or found no fault. Reported from a few thousand miles up to about 140,000 miles, with several cases between 40,000 and 90,000 miles.
What to check: Check the oil level and condition, look for a fuel smell in the oil, and ask for records of injector or engine repairs. A pre-purchase inspection with a scan for stored codes is worthwhile.
2 excerpts from owner complaints in NHTSA records
“I have a 2021 Hyundai Sonata SEL with a Smartstream 2.5L engine w/ GDI & MPI. I have have always heard a loud knocking noise coming from my engine since I got the vehicle when in park. When you are accelerating it hesitates and you can hear a knocking noise. I have taken it to the dealership multiple times and they were able to feel and hear what I was talking about but ensured me it was fine. Recently it has been a lot worse. On 10/18/2023 I was getting on to the highway from the feeder. …”
NHTSA complaint #11551474, filed 2023-10“This car has two problems. 2 weeks I was driving on the highway. All the sudden the shutoff and lost all power on the car. Thank god I pulled to the side of the road safely. Turned the car off and turned it back on. The car started to run normal. I took it to mechanic. They scanned the car with their computer. Said the car has no problems. Tested the battery and all other components. No problems found. This happened again yesterday on the highway driving. Car engine shuts off again. The car has engine problems as well. …”
NHTSA complaint #11628830, filed 2024-12 - Engine
Coolant loss and white smoke from exhaust (EHRS)
- 7 complaints (5%)
- typically at 5.4 yrs old
- filed 2023–2026
Owners report the coolant level dropping quickly with no visible external leak, the heater going cold, and thick white smoke from the exhaust that obscures the view behind the car. Some say the engine overheated and they had to pull over. According to complaints, dealers confirmed a failure in the exhaust heat recovery system, and one owner said the part was treated as a known issue. Reported mostly after 40,000 miles, sometimes noticed first in cold weather when the heater stopped working.
What to check: Check the coolant reservoir level and ask whether the exhaust heat recovery system or coolant-related repairs have been done. Watch for persistent white smoke on a test drive.
2 excerpts from owner complaints in NHTSA records
“Vehicle suddenly lost heat in 30 degree weather. No warnings, check engine light, or temperature gauge indicators came on. Lucky made it to a parts store and found out I was extremely low on coolant. Bought coolant and put it in. Made it back to the house and was immediately low again. No visible leaking. Oil was completely fine (1 gallon of coolant would have have left some kind indicator). Realized it was more than likely the ehrs. If this happened during the summer, my engine could have blown due to a poor design causing a major accident.”
NHTSA complaint #11718194, filed 2026-02“The internal core of the Exhaust Heat Recovery System (EHRS), part of the center muffler/front pipe assembly (#28600-L5210), suffered a catastrophic failure. This allowed approximately 9 gallons of engine coolant to leak directly into the hot exhaust stream. Safety Risk: This failure creates a severe visibility hazard. During acceleration from stop lights and stop signs, the vehicle emits massive, thick clouds of white glycol smoke. …”
NHTSA complaint #11727380, filed 2026-03
Buying note. Check that fuel-tank and transmission recall work has actually been completed, since several owners report parts delays, and get a pre-purchase inspection that includes a scan for stored codes and a look at coolant and oil levels.
Summary written with AI from a sample of 60 NHTSA complaints for this model year (picked at random, with complaints that state a mileage and recent ones taken first), then checked automatically against the source records. Where a problem shows a complaint count, every complaint for this model year was matched with fixed keyword rules (written with AI and tested against the sample), and the mileage, age and repair figures are calculated from those complaints; owners' figures are as stated, not verified. Other counts refer to the sample. The excerpts come from NHTSA's public complaint records and are unverified; capitalisation is normalised, NHTSA staff notes are removed, and shortened text ends with “…”. Something wrong? Request a correction.
NHTSA recorded 135 consumer complaints for the 2021 Hyundai Sonata. 25 of the complaints include a mileage, and 64% of those were filed for vehicles with under 50,000 miles; the median is 41,000 miles. Of all complaints, 7 involved a crash, 13 an injury, according to the filers. NHTSA lists 4 recall campaigns and 90 technical service bulletins for this model year. Compared with the other 15 Hyundai Sonata model years that have at least 25 complaints and are old enough to compare, this one scores 28 out of 100, where 50 is a typical year for the model (fewer complaints than typical for this model). The comparison allows for the era and for how long each year has had to collect complaints, but not for how many vehicles were sold.
Which parts are reported most
Complaints can name more than one part, so the counts add up to more than the total. Select a part to see its complaints, recalls and bulletins.
- Engine34 25%
- Fuel system34 25%
- Other or unknown32 24%
- Electrical system18 13%
- Air bags4 3.0%
- Brakes4 3.0%
- Body and structure4 3.0%
Also reported: Lane departure (3), Seat belts (2), Seats (2), Steering (2), Vehicle speed control (2), Engine cooling (1), Suspension (1).
Example complaints
Engine: “On i believe 1/14/26, my check engine light came on. Scheduled appt.for 1/16/26 for diagnostic. Several things were wrong. I decided to come back due to not having the money at the time. Over the wked, I remembered a recall notice i received around November that I asked about in November during my oil change & was told the parts aren't in & they'd give me a call. Upon viewing the recall it seemed some things I was told on 1/16/26 could be a result of the recall. …”
NHTSA complaint #11719681, filed 2026-02Fuel system: “Engine revving at a complete stop. Surging engine while braking. I was forced to put into neutral when stopping. I had check engine prior that read P049D85. It went away. The Hyundai dealer said to be the EGR valve. Nick Hayes at D'Arcy Hyundai and Hyundai Motor America (HMA) agreeing to a 75% goodwill split of cost to repair.”
NHTSA complaint #11753130, filed 2026-07Other or unknown: “I live northern suburbs of Illinois. I was backing out of a parking spot when I couldn’t switch gears from Reverse to Drive. My car showed flashing lights and said system malfunction and service immediately. I had to put the safety brake and turn of my car. It took a couple minutes to reset and turn on my car for me to move it.”
NHTSA complaint #11641099, filed 2025-02Transmission and drivetrain: “After initial startup and drive for a short time, I come to a stop. Then after vehicle doesn’t want to accelerate as it normally would. Vehicle struggles to gain speed but, the engine revs excessively. I pull off the road and come to a stop and try to accelerate again and the same thing happens. I shut the vehicle off and wait a few minutes,then restart and the vehicle accelerates normally again. There were no check engine lights the when this has happened.”
NHTSA complaint #11676441, filed 2025-07Mileage when problems were reported
64% of the 25 complaints with a mileage were filed for vehicles with under 50,000 miles; the middle half falls between 15,000 and 70,000 miles.
Complaints by year filed
Trend: rising. Complaints filed in the last 3 full calendar years are at least 25% higher than in the 3 years before.
Crash test ratings
NHTSA's 5-Star Safety Ratings for the 2021 Hyundai Sonata. Frontal results are shown driver / passenger; rollover shows the star rating and NHTSA's estimated risk of rolling over in a single-vehicle crash.
| Version | Overall | Frontal | Side | Side pole | Rollover |
|---|---|---|---|---|---|
| Sonata · sedan FWD | ★★★★★ | 4 / 5 | 5 | 5 | 5 · 9.7% risk |
| Sonata N · sedan FWD | not rated | — | 5 | 5 | 5 · 9.7% risk |
Driver aids listed by NHTSA for the 2021 model year: forward collision warning standard, lane departure warning standard, automatic emergency braking standard.
Neighbouring years: 2020: same overall rating; 2022: same overall rating. A redesign between years can change both the car and the test.
Source: NHTSA New Car Assessment Program (5-Star Safety Ratings), nhtsa.gov/ratings.
Fuel economy and running cost
EPA ratings for each 2021 Hyundai Sonata version. Annual fuel cost is the EPA's estimate at its current fuel prices for 15,000 miles a year (55% city driving).
| Version | Engine | Transmission | City | Hwy | Comb. | Fuel / yr |
|---|---|---|---|---|---|---|
| Sonata FWD | 1.6L 4-cyl | 8-speed automatic | 27 | 37 | 30 | $2,250 |
| Sonata FWD | 2.5L 4-cyl | 8-speed automatic | 28 | 38 | 32 | $2,100 |
| Sonata FWD | 2.5L 4-cyl | 8-speed automatic | 27 | 37 | 31 | $2,150 |
| Sonata FWD | 2.5L 4-cyl | 8-speed automatic | 23 | 33 | 27 | $2,500 |
Source: U.S. EPA and Department of Energy, fueleconomy.gov. Ratings are for comparing vehicles; real-world mileage varies with driving and conditions.
Recalls and investigations
- 25V796000Nov 17, 2025Fuel system, gasolineCovers: Hyundai Sonata 2020–2023
Hyundai Motor America (Hyundai) is recalling certain 2020-2023 Sonata vehicles. A damaged check valve can allow air to enter the fuel tank, causing it to expand and contact hot exhaust components, melting the tank.
- 22V746000Oct 6, 2022Power train › Automatic transmissionCovers: Hyundai Sonata 2021–2022, Santa FE 2021–2022, Veloster N 2021–2022 +3 more
Hyundai Motor Company (Hyundai) is recalling certain 2021-2022 Santa Fe, Sonata, Veloster N, 2022 Santa Cruz, Elantra N, and Kona N vehicles. The vehicle's "fail-safe" limited-mobility drive mode may be impaired, when prompted by a transmission oil pump…
- 21V00M000Dec 28, 2021Visibility › WindshieldCovers: Hyundai Sonata 2021, Santa FE 2020–2021, Elantra 2021
Hyundai Motor America (Hyundai) is recalling certain 2020-2021 Santa Fe, 2021 Sonata, and Elantra vehicles. During manufacturing, the windshield may not have been properly bonded to the vehicle, allowing it to detach in a crash.
- 21V524000Jul 9, 2021Fuel system, gasoline › Delivery › Hoses, lines/piping, and fittingsCovers: Hyundai Sonata 2021–2022, Santa FE 2021–2022
Hyundai Motor America (Hyundai) is recalling certain 2021-2022 Santa Fe and Sonata vehicles equipped with 2.5L turbocharged engines. Fuel may leak at the pipe connection between the high-pressure fuel pump and fuel rail.
Recall details for the 2021 Hyundai Sonata → · Check a VIN at nhtsa.gov/recalls
NHTSA investigations
- DP22003Loss of Motive PowerClosed · Sep 12, 2022
Technical service bulletins
TSBs are manufacturer notes to dealers about known repair procedures. They are not recalls and do not by themselves mean a vehicle has a fault. 90 on record; the latest 10 are shown.
- 11038458Oct 8, 2026Engine. 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…
- 11038456Oct 7, 2026Engine. 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…
- 11033840Jun 5, 2026Transmission and drivetrain. 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…
- 11031400Apr 18, 2026Engine, Electrical system. 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…
- 11032523Apr 10, 2026Air bags. 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…
- 11032522Apr 10, 2026Air bags. 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…
- 11029937Mar 3, 2026Transmission and drivetrain. 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…
- 11029906Feb 25, 2026Forward collision avoidance, Exterior lighting, Lane…. 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…
- 11028666Feb 5, 2026Engine. 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…
- 11027589Jan 7, 2026Fuel system. 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…
Other model years of the Hyundai Sonata
| Year | Complaints | Median mi | Recalls | Crash ★ | MPG | Score (50 = typical) | Trend |
|---|---|---|---|---|---|---|---|
| 2025 | 17 | 19,025 | 0 | 5 | 29 | — | Too new |
| 2024 | 47 | 2,000 | 1 | 5 | 29 | Too new to compare | Too new |
| 2023 | 88 | 18,500 | 2 | 5 | 31 | 18 · Fewer | Too new |
| 2022 | 95 | 31,000 | 3 | 5 | 31 | 20 · Fewer | Rising |
| 2021 | 135 | 41,000 | 4 | 5 | 31 | 28 · Fewer | Rising |
| 2020 | 182 | 2,778 | 4 | 5 | 31 | 49 · Typical | Rising |
| 2019 | 162 | 24,000 | 0 | 5 | 29 | 0 · Fewer | Rising |
| 2018 | 375 | 21,250 | 1 | 5 | 29 | 39 · Typical | Rising |
| 2017 | 767 | 55,000 | 3 | 5 | 28 | 59 · Typical | Stable |
| 2016 | 728 | 63,000 | 6 | 5 | 28 | 69 · More | Rising |
| 2015 | 1,153 | 56,000 | 9 | 5 | 27 | 100 · More | Stable |
| 2014 | 750 | 70,000 | 7 | 5 | 27 | 69 · More | Falling |
| 2013 | 1,917 | 78,000 | 9 | 5 | 27 | 100 · More | Falling |
| 2012 | 1,558 | 80,000 | 8 | 5 | 27 | 100 · More | Falling |
| 2011 | 3,379 | 75,000 | 14 | 4–5 | 26 | 100 · More | Falling |
| 2010 | 345 | 65,000 | 2 | — | 25 | 18 · Fewer | Falling |
| 2009 | 460 | 68,000 | 2 | — | 25 | 51 · Typical | Falling |
| 2008 | 425 | 62,000 | 3 | — | 24 | 45 · Typical | Falling |
| 2007 | 696 | 64,000 | 5 | — | 24 | Not compared (before 2008) | Falling |
| 2006 | 1,047 | 70,000 | 9 | — | 24 | Not compared (before 2008) | Falling |
| 2005 | 165 | 80,000 | 1 | — | 22 | Not compared (before 2008) | Falling |
| 2004 | 202 | 85,500 | 1 | — | 22 | Not compared (before 2008) | Falling |
| 2003 | 199 | 65,252 | 6 | — | 22 | Not compared (before 2008) | Stable |
| 2002 | 320 | 89,288 | 7 | — | 22 | Not compared (before 2008) | Falling |
| 2001 | 205 | 86,000 | 3 | — | 21 | Not compared (before 2008) | Falling |
| 2000 | 276 | 104,696 | 4 | — | 21 | Not compared (before 2008) | Falling |
| 1999 | 124 | 98,723 | 4 | — | 21 | Not compared (before 2008) | Stable |
| 1998 | 49 | 80,000 | 1 | — | 20 | Not compared (before 2008) | Stable |
| 1997 | 49 | 72,000 | 2 | — | 20 | Not compared (before 2008) | Stable |
| 1996 | 23 | — | 1 | — | 21 | — | Stable |
| 1995 | 66 | 125,000 | 2 | — | 21 | Not compared (before 2008) | Stable |
| 1993 | 26 | — | 1 | — | 20 | Not compared (before 2008) | Stable |
| 1992 | 22 | 94,600 | 1 | — | 20 | — | Stable |
| 1991 | 29 | — | 1 | — | 20 | Not compared (before 2008) | Stable |
| 1990 | 16 | — | 3 | — | 20 | — | Stable |
| 1989 | 11 | — | 3 | — | 20 | — | Not enough data |
All Hyundai Sonata model years · Best and worst years by complaints
Frequently asked questions
What are the most common problems with the 2021 Hyundai Sonata?
Owners of the 2021 Sonata most often describe fuel-system problems, especially a swollen fuel tank tied to recall 25V796000, and loss-of-power events where the car drops into a limited-mobility mode or shuts off while driving. The issues reported most often: Fuel tank swelling and strong fuel odor; Loss of power and fail-safe mode while driving; Engine stalling, knocking and oil loss.
How many NHTSA complaints does the 2021 Hyundai Sonata have?
NHTSA recorded 135 consumer complaints for the 2021 Hyundai Sonata as of Oct 27, 2026. Complaints are unverified consumer reports and may be duplicated or inaccurate.
What part of the 2021 Hyundai Sonata is reported most often?
Engine is named most often, in 34 complaints (25% of the total), followed by fuel system with 34.
Has the 2021 Hyundai Sonata been recalled?
NHTSA lists 4 recall campaigns for this model year. To check a specific vehicle, enter its VIN at nhtsa.gov/recalls.
How did the 2021 Hyundai Sonata do in NHTSA crash tests?
NHTSA's 5-Star Safety Ratings give the 2021 Hyundai Sonata 5 out of 5 stars overall. Ratings from different model years are only comparable when the vehicle was not redesigned in between.
What gas mileage does the 2021 Hyundai Sonata get?
The EPA rates the 2021 Hyundai Sonata (Sonata, 2.5L 4-cyl) at 31 mpg combined, 27 city and 37 highway, with an estimated annual fuel cost of $2,150 at 15,000 miles a year. Other engine and drive versions are rated differently.
At what mileage are problems with the 2021 Hyundai Sonata reported?
Among the 25 complaints that include a mileage, the median is 41,000 miles and the middle half falls between 15,000 and 70,000 miles; 64% were filed for vehicles with under 50,000 miles.
About this data. Data from NHTSA (ODI) complaints, recalls, TSBs and investigations, updated Oct 27, 2026. Complaints are unverified consumer reports and may be duplicated or inaccurate. Crash ratings are from NHTSA’s New Car Assessment Program. Fuel economy is from the EPA and DOE (fueleconomy.gov).
Complaint counts come from NHTSA’s public complaint database; we count each complaint once. The source records for this vehicle are on nhtsa.gov. Scores and trends are our own summaries of that data, described in the methodology. This page is not legal, safety or repair advice: for a specific vehicle, check its VIN at nhtsa.gov/recalls and ask a qualified mechanic. See an error? Tell us.