2023 Hyundai Sonata

Transmission problems began around 60,000 miles (but we didn’t know what it was) — jerking and hesitation, that worsened over time. We took the vehicle in (November 2025 ),at around 109,000 miles at which time they couldn’t find anything. I took it back in December and they recommended the spark plugs. We took the car back again in March at which time they recommended other little things. We took the vehicle back yet again on March 10 and told them to check the transmission. The dealership said “ As far as the transmission, we cant get it to really do anything so if you dont have an extended warranty we would recommend waiting until the issue gets worse and then put a transmission in it unless you wanted me to get you a price on it”. The vehicle has been at an authorized Hyundai dealership since the third week in June 2026 (because I wanted them to tell me why I had a bad transmission in my three year-old car) while awaiting resolution from manufacturer's consumer advocate (they took 60 days to resolve absolutely nothing). A replacement transmission was authorized on August 6. The manufacturer-supplied replacement was installed and found defective on August 27 (when I asked to test drive the car with a mechanic) it would not shift past 3rd gear. When I asked the dealer why I was not informed, prior to my picking up the vehicle, he told me “we don’t tell the consumer every little thing”. A second replacement was supposedly ordered from the manufacturer August 27, and is still not installed as of October 17. The manufacturer told me “the part was in and being worked on” 10/2. This was false. Th dealership is holding my vehicle hostage and demanding $5,786 for the defective replacement. My vehicle cannot be retrieved. The original transmission that was jerking and hesitating was a hazard to myself and other drivers around me, especially on the highway. The dealer even told me “ this is the third defective manufacturer replacement part received this month”.

NHTSA ID

11771807

Incident

Jun 22, 2026

While driving at highway speeds, the emergency brake system will apply and alert me. It’s happened twice now in the last 3 weeks. I’ve experienced a random loss of power while driving on the highway with no check engine light on the dashboard. Lastly, at lower speeds the car will randomly jerk while accelerating with no lights on the dashboard as well. I’ve gone to the dealership but they wanted to charge me a diagnostics fee to first look over the vehicle, which I don’t feel I should be on the hook for since the issue isn’t user caused.

NHTSA ID

11766459

Incident

Sep 22, 2026

When left turn signal is selected blinker nor camera comes on and at times it does work. Constantly in and out never steady. This never happened with the right turn signal only the left

NHTSA ID

11764561

Incident

Aug 24, 2026

I own a 2023 Hyundai Sonata SEL. Over approximately three years, the vehicle experienced four separate incidents involving sudden loss of engine power and recurring fuel injector/powertrain problems. Three of these incidents occurred while the vehicle was being driven on interstate highways, creating serious safety concerns. The first incident occurred on XXX, on [XXX] [XXX]. My daughter was driving the vehicle at the time when it suddenly lost power while traveling on the interstate. She had to maneuver the vehicle to the shoulder under unsafe traffic conditions. The second incident occurred on XXX, on [XXX] near [XXX]. I was driving the vehicle when it again experienced sudden loss of power while traveling at highway speed. The third incident occurred on XXX, in [XXX]. The vehicle experienced another significant power-loss event and required roadside assistance. The fourth incident occurred on XXX, on [XXX]. The vehicle again experienced a sudden loss of engine power while I was driving on the highway. Despite multiple repair attempts, including repairs related to the fuel injectors, the same or substantially similar power-loss problem continued to recur. Because the vehicle has repeatedly lost engine power while being driven, including multiple incidents at interstate highway speeds, I believe this recurring condition presents a serious safety risk. I am reporting these incidents so NHTSA can evaluate whether this may represent a broader safety-related defect affecting this vehicle model. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ID

11755422

Incident

Jun 30, 2026

The contact owns a 2023 Hyundai Sonata. The contact stated that while driving approximately 15-40 MPH, the vehicle was sputtering and shaking abnormally. The failure was a recurring failure. The contact associated the failure with NHTSA Campaign Number: 25V796000 (Fuel System, Gasoline); but the VIN was not under recall. The dealer was contacted; however, the vehicle was not diagnosed or repaired. The manufacturer was not made aware of the failure. The failure mileage was approximately 86,500.

NHTSA ID

11753540

Incident

Jul 16, 2026

Mileage

86,500 mi

The contact owns a 2023 Hyundai Sonata. The contact stated that while driving at an undisclosed speed, the transmission shifted into neutral(N) and failed to shift into park or drive on three occasions. The vehicle was restarted. After restarting the vehicle, the vehicle was shifted into drive, and the contact continued driving. The message that the vehicle could not be shifted into other gears was displayed. The vehicle was originally purchased in another state. The vehicle was taken to the local dealer to be diagnosed. The dealer determined that the battery and fuel injector pump needed to be replaced. The vehicle was repaired; however, the failure recurred. The manufacturer was not contacted regarding the failure. The failure mileage was approximately 50.

NHTSA ID

11744098

Incident

Jun 13, 2026

Mileage

50 mi

This is an extremely common issue plaguing Hyundai & Kia vehicles with the Theta III 2.5L Turbo engine, Such as Kia K5 GT, Hyundai Sante Fe, Hyundai Santa Cruz, & Hyundai Sonata N-Line. Its a failing ITM (integrated thermal management) unit or otherwise known as an ITMS unit. There is a rod within the ITM that prevents proper control of the flow of cooling the oil and engine coolant of the engine. Results in Cooling issues, such as a cold lower radiator hose while the engine is hot, or 'limp mode' during acceleration, that causes a sudden loss of power while trying to merge on the expressway. There has been other Kia models and years that have had TSB's related to fixing this issue, but Hyundai has released nothing. I have uploaded an example of one of the TSB's that do not apply to my car. Technical symptoms often include: Fans running 100% full duty (high) while the lower radiator hose stays cool. Or Fuel dilution or a 'rich' running engine. Because the engine is overcooling that keeps the car's fueling rich and in a open loop mode affecting emissions and contaminating oil. Personal Details of exactly what happened when i noticed mine was failing. I ran home on my lunch break, and while accelerating on a ramp to get up on a highway, my car started beeping and flashing "Engine Overheated" and i immediately let off the gas with preparation to pull over. The second i left off the gas, the coolant temp within 1-2 seconds went from a little over 3/4 the way up the gauge back to normal a little below half temp. I resumed driving a 3 mile drive back to work, with it showing normal temps the rest of the way. I popped the hood when i got to work to see if coolant was low, and it was completely normal, a little over halfway between the min/max lines. The car continues to run hot, often with the cooling fans running at 100%.

NHTSA ID

11737860

Incident

Feb 25, 2026

Was driving and stopped at a stoplight. When I went to drive it started sputtering and if I wouldn’t have driven into a gas station, it would’ve given out in the middle of the road. It wouldn’t let me switch to drive or reverse , only neutral or park. It threw a code P0301, cylinder 1 misfire. Had to get it towed. Now I have to get my spark plugs and fuel injectors replaced.

NHTSA ID

11737351

Incident

May 5, 2026

This bulletin provides information related to the navigation and head unit software changes introduced in the 2026 2nd Navigation Map and Software Update. The changes may vary depending on vehicle type, model, and navigation system. Refer to the 2026 2nd Navigation Map and Software Update Key Improvements and Additional Improvements tables in this TSB for a list of specific changes. The software can be downloaded via Navigation Updater (NAU) and updated by USB.

Some Hyundai vehicles may be equipped with a parking distance warning (PDW) sensor(s) that may trigger various DTCs and display warning messages on the instrument cluster, resulting in the PDW sensor(s) failing to detect nearby objects or triggering multiple false alarms. This condition may be a result of external damage to the PDW sensor membrane or sensor cover from rock chips or road debris, a collision, or previous vehicle repairs or modifications.

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 diagnosed with this condition. All internal combustion engines consume some engine oil during normal operation, depending on driving conditions and mileage, and this procedure should only be performed when deemed necessary based on inspection and diagnosis of the vehicle as outlined in TSB 26-EM-015H, Engine Oil Consumption – Inspection & Repair Guidelines, or the latest revision.

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 exhibiting this condition. All internal combustion engines consume engine oil as part of normal engine operation. Oil consumption rates may vary based on mileage, operating conditions, driving habits, and maintenance history. Hyundai recommends following the prescribed maintenance schedule and periodically checking the engine oil level using the dipstick to maintain proper engine oil level.

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 revises the touch point learning variation, improving drivability and judder symptoms. Some 8WDCTs (indicated by a new part number) received an updated clutch spring. The correct TCU software update must be matched with the correct corresponding 8WDCT hardware, otherwise, drivability concerns may occur. This service procedure should be performed prior to any 8WDCT replacements done for drivability/judder concerns.

This bulletin provides information related to the navigation and head unit software changes introduced in the 2026 1st Navigation Map and Software Update. The changes may vary depending on vehicle type, model, and navigation system. Refer to the 2026 1st Navigation Map and Software Update Key Improvements and Additional Improvements tables in this TSB for a list of specific changes. The software can be downloaded via Navigation Updater (NAU) and updated by USB.