2023 Hyundai Sonata

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)

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.

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%.

Vehicle WITHOUT WARNING will start to jerk then go into “limp” mode. Pressing on gas pedal makes the revving noise but with not physical movement made. This has happened on MULTIPLE occasions (13 times in 4 months) including in the snow and on the interstate while driving at 70mph where no shoulder is available to pull over. Car was taken to dealership 3 different times with no actual diagnosis, tests were ran all 3 times with nothing. Eventually the 3rd time at the dealership I was told the transmission was being replaced although they were not sure what actually caused the issue (this is written in the service report by the rep/mechanic). CAR REMAINS UNSAFE AND UNRELIABLE. Livelihood of myself, family and other drivers is at risk EVERYTIME I put the car in drive due to this mechanical issue. NO WARNINGS NO POWER NO FIX.

Car was parked, full stop, doors shut, seatbelt on. Foot on brake. Car then seemed to lurch forward by itself forward hitting parking cement block. Put in reverse to back away and car stayed still...then I tapped the gas again to back up and insted vehicle plowed forward.instead.of reverse ...went over the parking block and hit concrete beam in front, when the car should have backed up in reverse. I'm a person who drives speeed limits, and ulta careful when i drive, and parked at this place/spot for years. This has never happened not sure why it did. No injuries or other people involved thank god, but scared the heck out of me. Wracking my brain, my recalls and software and service appts are up ro date.Nothing out of ordinary that day. I'm confused and shaken, why the first lurch forward and why did going in reverse move it forward? ugh. It drove home fine. Commute to work daily for years, no issues. All I can guess is gear didn't click to reverse and was somehow in drive? Ive been going over the possibilities in my head for human error but they dont make sense - again I've been driving for 40 years. If it happens to other models, would love to know! Car will go to repair tomorrow as "my fault" via insurance, hoping they can see more if any error codes, to at least say if Reverse didn't engage or something else happened. May have been human error but it's so out of the ordinary for me. Thanks!

At least 8 times when driving the car the transmission switches from the drive “d” position to the park “p” position and I have to cut off the car and then restart. It is very dangerous as I can be rear ended which can result in personal injury as well as an insurance claim. I’ll put the last date it occurred but started experiencing soon after I bought car.

On January 6, 2026, during my morning commute in heavy traffic, my 2023 Hyundai Sonata engine unexpectedly turned off, causing a sudden loss of power. This created an extremely dangerous situation, and I came very close to being involved in a major collision. While I was fortunate to avoid a crash, the incident posed a direct threat to my safety and life because of the dense surrounding traffic.

2023 Sonata N-Line, complete loss of power while driving on seven (7) occasions over the past year. In all cases above 60mph creating a dangerous condition to myself and fellow drivers while attempting to pull to the side of the road while rapidly losing speed. In all seven (7) cases, the DTC code is P065312. I have asked the dealership to note the recurring issue in my service records and I have reached out to Hyundai, mostly so that if I am involved in a serious accident because of this issue, there is a paper trail for legal purposes. The dealership folks are nice but basically unless the car rolls into the dealership with smoke pouring out of the engine, they want to charge a diagnostics fee and keep the car for multiple days which isn't helpful because like most, I need the car and the issue is extremely sporadic. It is disappointing and I hope Hyundai takes note and provides remedy for the issue sooner rather than later as this is my sixth (6th) Hyundai vehicle and really do like the car otherwise. All incidents below: 01/23/2025 - 9531 miles 01/20/205 - 9128 miles 12/15/2024 - 5500 miles 12/13/2024 - 5374 miles 11/22/2024 - 2409 miles 01/12/2024 - 568 miles 01/08/2024 - 554 miles

For like the fifth time while I'm driving the car just dies. I can be going 55 I can be going 70 and the dashboard lights up like a Christmas tree and the car just dies. I have to pull the car over to the side and I have to turn it off and restart it again. And then about 3 days later the check engine light will go away. This seems like a software issue but Hyundai and my local dealer cannot help me I'm going to get killed in this thing. I can't take it on the highway I can barely take it down the street because it could go out on me while I'm driving and I could be in the middle lane and I could get killed. They tell me they can't replicate the issue but it's a software issue somebody needs to do something before I get killed. Every single light on the dashboard turns on and the engine just dies. This is like the fifth time this has happened. I think this car is a lemon but no one will help me.

On 4 occasions in the last 4 months when I push the gas my cars rpm will go up but the car does not accelerate. This has happened twice on the interstate when trying to merge with trsffic and twice in city traffic, once when making a lefthand turn across oncoming traffic and once just driving down the road. I have taken the car to 2 separate dealerships for a total of 3 times and they drive it a few miles and tell me they can't duplicate the issue. I just picked my car up today after leaving it for 6 days. On my way home the emergency breaking system activated for no reason slowing my car down on the interstate. Both of these issues could get me or someone elas killed. I have not even had this car for 2 years and I am afraid to drive it. Please help. I know I am not the only person with this issue because I can see others on the internet who also have been told that the dealership can't dupe the problem. Even the dealership I just picked it up from said they had another car there with the same problem that they can't duplicate so there is nothing they can do.