2020 Hyundai Sonata Power Train

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 light activation before complete power loss occurred. Manufacturer Inspection: Hyundai technical assistance case #[XXX] was opened for the third failure, acknowledging the recurring nature of this defect despite multiple repair attempts. Assessment: This appears to be a systematic manufacturing defect in the transmission control system affecting safety. Despite three different repair approaches by Hyundai, the identical P0768 error continues to recur, suggesting a fundamental design or manufacturing flaw that creates ongoing safety risks for drivers. The vehicle was out of service for 44 total days across these three incidents, indicating the severity and complexity of this recurring safety defect. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

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.

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.

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.