2020 HYUNDAI SONATA Power Train Problems

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

My certified pre-owned 2020 Hyundai Sonata has experienced the same critical transmission failure three times since October 2024, creating dangerous safety conditions on highways and city streets. Component/System Failed: Transmission control system with consistent P0768 error code (Shift Solenoid D Circuit Fault). Safety Risks: The transmission failures cause sudden power loss and inability to accelerate while driving, including on highways at speed. This creates immediate danger to myself, passengers, and other drivers when the vehicle unexpectedly loses power during traffic situations requiring acceleration or merging. Problem Reproduction: The failure has been confirmed and reproduced by authorized Hyundai dealership three separate times: - [XXX]: P0768 error, replaced shift control solenoid valve - [XXX]: Same P0768 error returned, replaced entire transmission control unit - [XXX]: Same P0768 error again, replaced complete control wiring harness with extensive dashboard removal Warning Signs: Each failure was preceded by transmission hesitation, rough shifting, and check engine...

My 2020 Hyundai Sonata has a recurring defect in its engine or transmission, causing sudden deceleration to ~10 mph without warning, often on major highways, with warning lights (check engine, ESC, traction control, etc.) flashing seconds before the car decelerates. This forces me to swerve off busy roads, endangering me, my passengers, and other drivers. Near-misses with traffic pose an extreme safety risk, causing significant emotional distress. The car, at a Hyundai dealer since April 21, 2025, is available for NHTSA inspection. The issue began in January 2021, five months after purchase, with all the warning lights appearing during incidents along with rapid deceleration. The Hyundai dealer confirmed the problem in seven repair attempts (January 2021, December 2021, January 2022, November 2024, February 2025, and twice in April 2025) but never properly diagnosed or fixed it, citing no consistent diagnostic codes. Only the dealer assessed it; no inspections by Hyundai’s...

My 2020 Hyundai Sonata has a recurring and dangerous defect involving sudden deceleration while driving. Without warning, the car abruptly slows to ~10 mph—often on the highway—while numerous dashboard warning lights activate. This poses an extreme safety risk to me, my passengers, and other drivers, as it forces me to maneuver off the road to avoid being hit. The issue began in January 2021, still with less than 4,000 miles and just five months after I purchased the car new. It has occurred repeatedly and unpredictably since then. I have taken the vehicle to a Hyundai-authorized dealer for repair on five occasions (January 2021; December 2021; January 2022; November 2024; and February 2025), but the problem has never been properly diagnosed or fixed. In November 2024, the issue occurred immediately as I drove off the dealer's lot, having been assured the vehicle was repaired and safe to drive. The most...

My 2020 Hyundai Sonata has a recurring and dangerous defect involving sudden deceleration while driving. Without warning, the car abruptly slows to ~10 mph—often on the highway—while numerous dashboard warning lights activate. This poses an extreme safety risk to me, my passengers, and other drivers, as it forces me to maneuver off the road to avoid being hit. The issue began in January 2021, just five months after I purchased the car new. It has occurred repeatedly and unpredictably since then. I have taken the vehicle to Hyundai-authorized dealers for repair on five occasions (January 2021; December 2021; January 2022; November 2024; and February 2025), but the problem has never been properly diagnosed or fixed. In November 2024, the issue occurred immediately after I picked the car up from the dealership when they told me it was fixed and ready to drive. This most recent occurrence (February 2025) before tonight's...

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. We were told that our vehicle should have never...

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...

I was on my way back home from Alexandria LA on [XXX] 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. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Vechile shut down completely on the highway, engine's been replaced twice, Catalytic converter, Turbo was replaced three times, Battery oxygen sensors, timing belt all have been replaced, Along with my wireless charger and Both heaterhouses and splash guard. I recently had my vehicle SERVICED Thirty five hundred miles after NEW engine install The dealership serviced my car didn't reset my service indicator 3 weeks later, my vehicle without warning said Engine overheated, so I pulled over immediately that display went off. My actual thermostat stayed under the center line in between cold and hot. I contacted the dealership and got my vehicle into BE inspected At that time, they said my coolant level was low and both heapeer. Hoses needed to be replaced and my engine needed to be flushed and refilled. I had those services completed. I picked up my car 5/24 it was OK on 5/25 My service...

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.

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...

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.

When accelerating hard (pedal to the floor) from approximately 55 mph, the transmission may not downshift correctly and loses power causing a safety issue. When attempting to continue accelerate at full throttle, the RPMs hang while simultaneously losing vehicle speed. Other symptoms noticed were slight vehicle jerkiness from RPMs bouncing up and down a couple of hundred RPMs. When letting off of the accelerator to a "normal" depression level, the vehicle upshifts into an appropriate gear and will gain speed (though sluggish). In the same drive (meaning the ignition was not turned off then back on) , if attempting to push accelerator to the floor, the same results happen as stated before. Also in the same drive (after exiting the highway), from a stop at a red light I tested the issue again with the same results. No warning lights, messages, or other symptoms were present to indicate a malfunction....

Car is 20 months old and in that period the car has experienced on at least 3 occasions a problem with acceleration. After stopping and then attempting to accelerate the transmission had a problem engaging and increasing speed. It took probably 30-40 seconds to get from zero to 25 or so then engaged back to normal. Obviously dangerous if getting onto highway or turning in traffic. Dealership cannot replicate problem so they cannot analyze. Last instance was about 2 months ago March 2022. Similar to other incidents posted here.

1.TRANSMISSION DOES NOT FUNCTION PROPERLY AT ALL TIMES. IT SLIPS FROM TIME TO TIME UPON ACCELERATION, (RIGHT AFTER DECELERATION), INCREASING THE ODDS OF A COLLISION WHEN ATTEMPTING TO AVOID OTHER VEHICLES ON A COLLISION COURSE WITH MINE. 2.NOISE FROM STEERING COLUMN 3. THREE TRIPS TO DEALER HAVE BROUGHT NO RESOLUTION

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.

TL* THE CONTACT OWNS A 2020 HYUNDAI SONATA. THE CONTACT STATED WHILE DRIVING 35 MPH AND ENTERING THE HIGHWAY, THE VEHICLE WOULD NOT SHIFT INTO GEAR AND THE VEHICLE WAS SPUTTERING. THE CONTACT STATED THAT THE VEHICLE WOULD NOT EXCEED 45 MPH. THE CONTACT PULLED ONTO THE SHOULDER OF THE HIGHWAY AND SHUT-OFF THE VEHICLE. NO WARNING LIGHT WAS ILLUMINATED. THE CONTACTED RESTARTED THE VEHICLE HOWEVER, THE FAILURE PERSISTED. THE CONTACT PULLED OFF THE HIGHWAY AND HAD TO RESTART THE VEHICLE SEVERAL TIMES. THE VEHICLE WAS TAKEN TO THE LOCAL DEALER - WEBB HYUNDAI MERRILLVILLE (1000 81ST AVE MERRILLVILLE IN 46410, (219) 249-4961) WHERE THE DIAGNOSIS WAS NOT DETERMINED FOR THE ENGINE HOWEVER, THE CONTACT WAS INFORMED THAT THE HEATING SYSTEM WAS FAULTY AND THE INSTRUMENT PANEL FAILED TO PROVIDE AN ACCURATE WARNING LIGHT FOR THE FAILURES. THE VEHICLE HAD NOT BEEN REPAIRED. THE MANUFACTURER WAS NOTIFIED OF THE FAILURE...

OCCASIONALLY THERE IS A SERIOUS DELAY WHEN TRYING TO ACCELERATE. CAR TENDS TO JERK/BUCK WHEN ACCELERATING, USUALLY IN THE LOWER GEARS. I HAVE NO IDEA IF THIS IS A TRANSMISSION ISSUE OR A FUEL INJECTION ISSUE, BUT MY DEALERSHIP HAS NOT BEEN ABLE TO DETECT AN ISSUE AND KEEPS TELLING ME EVERYTHING IS NORMAL WHEN IT CLEARLY ISN'T. THE CAR ALSO HAS HARSH DOWNSHIFTS ESPECIALLY GOING FROM 2ND TO 1ST GEAR.

FOLLOWING A FIRMWARE UPDATE TO THE OBC FOR A RECALL, THE VEHICLE TRANSMISSION NOW HAS A SEVERE DELAY RESPONDING TO DRIVER INPUT. THE TRANSMISSION IN THIS VEHICLE HAS ELECTRONIC SHIFT WITH PUSHBUTTONS. PREVIOUS TO THE FIRMWARE UPDATE, THE TRANSMISSION WOULD RESPOND INSTANTLY TO DRIVER INPUT FROM THESE BUTTONS. FOLLOWING THE FIRMWARE UPDATE, THE TRANSMISSION TAKES TWO SECONDS TO RESPOND. THIS DELAYED ACTION PROHIBITS DRIVER EMERGENCY SHIFTING, CREATING SEVERE RISK OF AN ACCIDENT. IN MY VEHICLE, I RECENTLY WAS ALMOST INVOLVED IN A TRAFFIC ACCIDENT WHEN THE DELAYED RESPONSE FROM THE TRANSMISSION CAUSED MY VEHICLE TO REVERSE INTO THE OPPOSING LANE OF TRAFFIC AS ACCELERATION WAS ATTEMPTED THINKING THE VEHICLE HAD SHIFTED INTO DRIVE. UPON ENTERING THE ACTIVE OPPOSITE LANE OF TRAFFIC, EMERGENCY ACCIDENT AVOIDANCE WAS PROHIBITED BY THE DELAYED RESPONSE OF THE VEHICLE SHIFTING INTO 'DRIVE' IN ORDER TO MOVE THE VEHICLE FROM THE OPPOSITE LANE OF TRAFFIC. PREVIOUS TO...

VEHICLE ABRUPTLY STOPPED IN A TRAFFIC SIGNAL WITHOUT GIVING ANY INDICATIONS WHAT SO EVER. WHEN TRIED TO RESTART IT STALLED PRETTY BADLY CAUSING EXCESSIVE VIBRATIONS. THIS HAD JUST 1900 MILES ON IT. VEHICLE DIDN'T HAVE ANY MIL OR ANY VISIBLE INFORMATION ABOUT THE ISSUE. IT CREATED A HUGE TRAFFIC PILE UP DUE TO THE PEAK HOUR IN WHICH THIS PROBLEM STARTED. FEW DAYS AGO THERE WAS ISSUE WITH STARTING BUT IT RESOLVED AFTER COUPLE OF MINUTES, THIS TIME THE VEHICLE HAD TO BE TOWED TO THE DEALERSHIP AND I LOST MY DAYS WORK AND PAY. BIGGEST CONCERN IS HOW ABRUPTLY IT STOPPED IN A BUSY STREET.

VEHICLE ROUGH IDLED & EVENTUALLY SHUDDERED TO A STOP. THIS HAPPENED FOUR TIMES WHILE IN GEAR AND IDLING AT APPX 1000-1500 MILES. BETWEEN 1500-2000 MILES, VEHICLE SHUT DOWN WHILE DRIVING APPX 60MPH ON A COUNTY ROAD. AT APPX 2700 MILES, MPGS DRASTICALLY IMPACTED WHEN VEHICLE SUDDENLY STOPPED SHIFTING GEARS PROPERLY WHILE IN MOTION AT APPX 70MPH ON THE HIGHWAY. CHECK ENGINE LIGHT APPEARED WITH MESSAGE REGARDING ECS ISSUES. VEHICLE STILL DRIVES, IT JUST SEEMS TO STRUGGLE WITH EFFICIENCY AND SHIFTING CORRECTLY.