2021 Hyundai Sonata
Problems, recalls and owner-reported issues
Engine is the leading concern among 134 owner complaints filed for this model year. This is the 22nd highest complaint count among 26 Sonata model years with reports.
Of the 2021 reports, 7 involved a crash. 13 people were injured.
What owners report most often
Recalls and investigations
Fuel system, gasolineNov 18, 2025
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.
A melted fuel tank can leak, increasing the risk of a fire.
Dealers will inspect and replace the check valve. The fuel tank assembly will be inspected for damage and replaced if necessary. Additionally, dealers will inspect and update the engine control unit software. All repairs will be performed as necessary, free of charge. Owner notification letters were mailed beginning March 13, 2026. Owners may contact Hyundai customer service at 1-855-371-9460. Hyundai's number for this recall is 286. Vehicle Identification Numbers (VINs) involved in this recall became searchable on NHTSA.gov on November 19, 2025.
Campaign 25V796000 on NHTSA.gov
Power train, automatic transmissionOct 6, 2022
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 malfunction, which can result in a complete loss of drive power.
Loss of drive power increases the risk of a crash.
Dealers will inspect and replace the transmission, as necessary. Dealers will also update the transmission control unit software. All repairs will be performed free of charge. Owner notification letters were mailed January 10, 2023. Owners may contact Hyundai customer service at 1-855-371-9460. Hyundai's number for this recall is 236.
Campaign 22V746000 on NHTSA.gov
Visibility, windshieldDec 28, 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.
A windshield that detaches from a vehicle during a crash can increase the risk of injury.
Dealers will remove and reinstall the front windshield panel, free of charge. Owner notification letters were mailed June 20, 2022. Owners may contact Hyundai customer service at 1-855-371-9460. Hyundai's number for this recall is 216.
Campaign 21V00M000 on NHTSA.gov
Fuel system, gasoline, delivery, hoses, lines/piping, and fittingsJul 9, 2021
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.
A fuel leak increases the risk of a fire.
Dealers will inspect and tighten, or replace the fuel pipe as necessary, free of charge. Owner notification letters were mailed on September 3, 2021. Owners may contact Hyundai customer service at 1-855-371-9460. Hyundai's number for this recall is 207.
Campaign 21V524000 on NHTSA.gov
Representative owner complaints: engine
35 reports, newest first. Show all
Engine, Oct 23, 2023
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. I tried to accelerate to about 50 mph and I heard the same knocking noise and my rpms jumped all the way to the top. Then my car suddenly stopped getting on to the highway. It took it about a minute before I could start driving again. Luckily there was no one behind me because it could've been really bad. I got home and looked under the hood and it looked like oil had sprayed out of the engine. You could to see oil splatter on the fender. No one was hurt thankfully. I have been complaining about the knocking and hesitation while accelerating for almost 2yrs.
Engine, Sep 25, 2023
The contact owns a 2021 Hyundai Sonata. The contact stated while driving 45 MPH, the vehicle inadvertently lost motive power in the middle of the roadway and failed to restart. The vehicle was pushed to the shoulder of the roadway, where the failure persisted. No warning lights were illuminated. The vehicle was towed to the dealer, who determined that there was no oil in the engine, causing the engine to seize. The vehicle was then towed to another dealer, who confirmed the diagnostic results. The contact stated that an oil change was performed three days prior to the failure. The vehicle was not repaired. The manufacturer was notified of the failure, and a case was opened. The failure mileage was 44,000.
Engine, Jun 13, 2023
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. Since then, I have had loss of boost and acceleration when passing around cars which has almost caused accidents, oil temps constantly running very high and fans constantly running on full blast even after car is off. I have been to the service center 4 times, and they have failed to "replicate" the issue and stated the fan and oil problem is "normal" which it is not. This problem needs to be addressed before somebody gets seriously hurt due to loss of power unexpectedly while driving. PLEASE help! Thank you for your time.
Engine, Fuel/propulsion system, Jun 8, 2023
When attempting to pass other vehicles or under quick acceleration such as an on ramp to the highway, the vehicle will experience a sudden loss of power and oil pressure resulting in a fail safe mode which limits your acceleration and causes a sudden decrease in speed and velocity. The issue results in the oil pressure light illuminating and requires the vehicle to be stopped and completely turned off to reset then once turned back on, the problem is “gone” until a sudden acceleration occurs again, which results in the same issue happening. There is a current recall out for similar models but my vin is not listed. I have approximately 50k miles on the car, and am the first owner.
Engine, Mar 11, 2023
My 2021 Sonata has 32,000 miles & it broke down in the middle of the road. My safety & my daughters safety were at risk. We could have been hit or killed. There were no warning lights. It had to be towed. Repair shop reports the transmission is no good. This vehicle should not have transmission issues. Hyundai will not even cover a rental car. The dealership can’t even work on it for 1-2 weeks. I work & have kids. I need a vehicle. The car breaking down in the middle of the road with no warning is dangerous.
Engine, Fuel/propulsion system, Nov 10, 2022
Oct 12: Engine stalled exiting I95 in Kittery Maine. Engine light flashed but did not stay on. Was able to get to safe place but car would not go more than 15mph. Hampton Huyndai reported mis-fire but stated it cleared on its own. Oct 17th: Engine stalled on highway ramp to I495, nearly causing me to be rear ended by other vehicles. Car would not go more than 15 mph. Engine light stayed on. Towed car to Key Salem Hyundai, defective injectors, warrantee repair. Oct 23rd: Car stalls on I93, was able to take immediate exit and turn engine off. Engine light flashed but did not stay on. Took car in to Salem dealership on Oct 24th, no code found. Oct 25th: Car stalls again on city street. Light stays on, Salem dealership replaces cat. convrtr between Oct 26th through Nov 4th. Nov 9th: Car stalls again on city street. Light stays on, currently in Salem dealership. This is a safety issue, in two cases already this car has nearly gotten me in an accident on the highway. I am seeking arbitration for replacement. I am scared to drive this vehicle. I will have a third invoice pending this next repair.
Power train, Engine, Nov 4, 2022
The contact owns a 2021 Hyundai Sonata. The contact stated while driving 65 MPH and attempting to accelerate, the vehicle failed to respond with the check engine warning light illuminated. The contact also heard a knocking sound coming from the vehicle. The contact pulled over on the side of the road and turn off and restarted the vehicle and the vehicle started operating as designed. The vehicle was taken to the dealer and the contact was informed that the transmission and engine needed to be replaced. The manufacturer was contacted but offered no assistance. A case was filed. The failure mileage was 2,700.
Electrical system, Engine, Fuel/propulsion system, Oct 8, 2022
UNKNOWN
Vehicle speed control, Engine, Sep 22, 2022
Since we purchased this brand new vehicle, we have had in the dealership service department at a minimum of 5 times for same issue. The vehicle accelerates while stopped at a light so we have to put it in neutral to keep it from accelerating. Once we take out of Neutral and release the break, the vehicle accelerates rapidly without stepping on the gas pedal. The computer system always comes on warning that we need to take to dealership because there are engine problems. Then it goes off and comes on again. We have contacted Hyundai to file a complaint and it has gone no where. We have taken it to Hyundai dealership in Tucson and they keep replacing parts per Hyundai manufacturer service tech reps. per same Egr codes. We are taking the vehicle to the dealership again today 9/22/22 because it started again around 9/1/22 and we have been waiting for a loaner car again from Dealership for same problems. Meawhile, being forced to drive it due to only owning 1vehicle. Hyundai Manufacturer has continued to have dealership change out parts and this keeps happening. The vehicle has just over 25K miles on it to date. The first time we had it in the dealership for this problem was on 4/6/22. We have almost rearended several vehicles and are scared to death to drive this vehicle. It is a safety hazard. We purchased the 2021 Sonata vehicle brand new on 11/24/21 along with the lifetime parts and labor warranty. It had 15 miles on it. We also traded our 2018 Hyundai ELantra. We paid off the 2021 Sonata completely in 2021. The total cost of this transaction was $34,294.74.We have also followed all the Maintenance requirements. It is urgent that this complaint is investigated as soon as possible and Hyundai Manufacturer take responsibility now before someone gets killed. The vehicle is obviously a dangerous manufactured vehicle.
Engine, Dec 2, 2021
The contact owns a 2021 Hyundai Sonata. The contact stated that while the vehicle was at an independent mechanic for an oil change, the mechanic diagnosed the vehicle with transmission fluid leaking from the engine. The mechanic informed the contact that the transmission fluid leakage was flammable. The dealer was made aware of the failure but informed the contact that they were backed up with other vehicles and could not diagnose the vehicle for approximately three weeks. The vehicle was not repaired. The manufacturer was made aware of the failure and a case was opened. The failure mileage was 5,600.