Mileage when the problem started
Owner reports
Selected complaints filed with NHTSA by 2020 Hyundai Sonata owners, lightly cleaned up (personal details are redacted by NHTSA).
The contact owns a 2020 Hyundai Sonata. The contact stated that while her husband was driving 75 MPH, the brake warning light appeared on the instrument panel as the vehicle began to hesitate upon depression of the accelerator pedal. The contact stated that the vehicle decelerated to 20 MPH as her husband pulled to the side of the highway and turned off the vehicle. The contact called the dealer and was given suggestions on how to correct the failure; however, none of the options worked. After some time, her husband restarted the vehicle and the vehicle resumed normal operation. The next day, the contact stated that the brake light returned upon start of the vehicle. The manufacturer was not notified of the failure. The vehicle was not repaired. The failure mileage was approximately 19,000.
The contact owns a 2020 Hyundai Sonata. The contact stated that the vehicle hesitated while depressing the accelerator pedal, with the check engine warning light illuminated on the instrument panel. The vehicle was taken to several independent mechanics and dealers to be diagnosed; however, the cause of the failure was not determined. The contact stated that one mechanic replaced an unknown sensor, but the failure returned soon after the repair. The manufacturer was notified of the failure. The vehicle was not repaired. The failure mileage was approximately 101,000
The contact owns a 2020 Hyundai Sonata. The contact stated that while driving at an undisclosed speed, the shift assists malfunction warning light illuminated. The contact turned the vehicle off and restarted the vehicle. The vehicle was towed to the dealer; however, the failure could not be duplicated. The vehicle was not repaired. The vehicle was not diagnosed or repaired by an independent mechanic or dealer. The manufacturer was not made aware of the failure. The failure mileage was approximately 21,000.
On or about November 13, 2024 our Hyundai Sonata 2020 gas tank almost exploded. We drove our vehicle to a dealership so that it could be checked because we kept hearing something that sounded like a loud pop / thumb underneath our vehicle. We had already been receiving notifications of a powertrain issue with the vehicle for years (without the dealership resolving the issue). So we were taking the vehicle in for numerous reasons when, the minute we drove our vehicle into the service bay (of a new and unrelated dealership) we were told that Hyundai's Corporate branch has ordered our vehicle grounded and told us we COULD NOT LEAVE with our vehicle or drive our vehicle off the dealership's lot. We were advised that our vehicle had almost exploded and that we were lucky to have brought the vehicle in. …
I believe the transmission malfunctioned as I reached 60 MPH / 4000 RPMs on the highway when it suddenly did not want to accelerate past that. The more I stepped on the gas pedal, the more it slowed down. I attempted to use the paddle shifters to shift up or down, but I was unable to shift up and shifting down did not allow me to accelerate past 4000 RPMs. The flow of traffic was faster than I could keep up with, and not being able to accelerate made it unsafe to be on the highway. I had to pull over, and get off of the highway. I found that others have reported this same issue online with the same make/model/trim, but I have not had time to take it in to be looked at. No warning lamps, messages, or other symptoms prior to failure. I only noticed when I got on the highway and needed to reach speeds greater than 60 MPH. …
Engine leaks oil. I went to the dealer and they blamed the other Hyundai dealer saying they stripped out the drain bolt. After all the back and forth they told me they will replace the drain pan. I scheduled to have the car dropped off and wasn't given a loaner. When I went to pick up the car they told me the ac bolt and bracket are broken and to come on Monday but the drain pan has been replaced. I went home and the car continued to leak oil and when I went back to the dealer and called them out they came up with every excuse in the books. Bolt is stripped, impact to pan, and so on. Long story short I went to fix the oil pan and they damaged the ac bolt so instead of telling me to come back to do everything they said they did the drain pan but the bolt would have to be done another day. I am waiting on a loaner car as I waisted a whole day without a car and the issue wasn't fixed. …
The transmission since we got the vehicle has had random hard shifts. The software updates seemed to have alleviate some of the occurrences. How ever when it does happen now. The whole car shakes while at idle and shifts extremely hard. Almost like braking hard. The problem has not been reproduced at a dealership yet, taking it in ASAP for inspection. Noting relating to the power train has been replaced. Just a software update a while back. No warning lights came on the screen when it happened. My wife was going about 20 miles per hour when she tried to accelerate. It was hesitant than shifted hard, lurching forward than accelerated. When she came to a stop at the next light it was shaking the whole car.
I was on my way back home from Alexandria LA on [redacted] when I heard like the sound of an blow out tire but wasn't happen to look in back of car and seen back seat was blown off the area of the car and proceeded to see that the gas tank was expanded like you would see a balloon and the me car started running funny and. Then a service code comes across the screen of the radio po45100 , so I pull over and look beneath the car and see that the gas tank is so expanded it's now pressing against the exhaust pipe. So I turned car off and here we are now I'm without a car due to this.
For my vehicle the Check Engine light has been on continuously throughout the last 6 months and mechanics are going to have to replace the thermostat. Multiple auto mechanics have indicated online that this is a very common problem with many Hyundai vehicles from 2020-2023 and can be a danger due to temperature control not being accurate for vehicles (Code P2181). Many owners of these Hyundai vehicles have experienced this issue leading online and this issue should be made aware to Hyundai and the general public to see if this is something that needs to be made aware for the safety of drivers to determine if their vehicle is at an accurate temperature.
My vehicle while driving, it is jerking and shaking. When I come to a stop, the cars rpms go up and down while the car is shaking. When I pressed the gas pedal to accelerate the car will not accelerate as normal and the car jerks as I'm driving it. The RPMs rev up and down without any pressure placed on the gas pedal. The check engine light came on.The miles per hour only allows me to put one digit. I wanted to clarify that the problem is occurring anywhere between 0 mph to 65 mph when these the car jerks and shakes and the RPMs go up and down without me pressure on the gas pedal.
Transmission complaints in other Sonata years
Frequently asked questions
How common are transmission problems on the 2020 Hyundai Sonata?
NHTSA has 24 complaints about the transmission & drivetrain of the 2020 Hyundai Sonata, 13% of the model year's 181 complaints.
Is there a recall for 2020 Hyundai Sonata transmission problems?
No. NHTSA lists no transmission & drivetrain recall for the 2020 Hyundai Sonata, though it has 4 recalls for other components. If the problem is widespread, a repair may still be covered by an extended warranty or a manufacturer service bulletin — ask a dealer.
At what mileage do 2020 Hyundai Sonata transmission problems start?
Half of the complaints with a recorded mileage happened before about 19,000 miles, and 88% before 25,000 miles.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) — owner complaints through October 20, 2026, recalls and defect investigations; fuel economy from the EPA. Complaints are unverified reports and are not proof of a defect. How we rate model years.