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 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.

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%.

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.

The contact owns a 2023 Hyundai Sonata. The contact stated that while his wife was driving at an undisclosed speed, the message "Engine Overheated" displayed. The contact checked the Hyundai app, but it showed no failure. The contact's wife drove to their son's residence, who inspected and discovered that there was no coolant in the engine. The contact's son added coolant to the engine. The vehicle was taken to the dealer, who replaced the coolant valve, exhaust muffler assembly center, clamp assembly exhaust pipe, two gasket exhaust pipes, and added coolant. The contact related the failure to Technical Service Bulletin: 23-EM-009H (EHRS Coolant Leak Repair); however, the vehicle was not covered under the TSB. The manufacturer was made aware of the failure, and a case was filed. The failure mileage was approximately 18,500.

Battery Management System completely exhausting the 12V battery resulting in the car acting as if it has no power. When this happens, you can't unlock the door or open the trunk. On two separate occasions, I have encountered a complete loss of power in my Sonata Hybrid, preventing me from unlocking the trunk or doors upon returning from extended trips. The first incident occurred after a ten-day absence last Fall, and the most recent was on Saturday, March 14, 2025. During the latest incident, I returned from a seven-day trip and found my vehicle parked at Orlando International Airport. Upon approaching the car, I anticipated being able to unlock the trunk, load my luggage, enter the vehicle, and drive home. However, once again, the vehicle was unresponsive. Accessing the car required removing the cap from the door handle and manually inserting the key, a process that took approximately ten minutes, which was particularly inconvenient and concerning in an airport parking lot. This situation was even more challenging considering I am a [XXX] woman of smaller stature attempting to resolve this issue alone at night. I believe this poses a serious safety concern for all owners under similar circumstances. Following the incident last Fall, I brought my Sonata Hybrid to Key Hyundai in Jacksonville. I was informed that this is a known issue for which there is a recall; however, my vehicle model year is not included in the affected range. It was suggested that I would need to manage this problem independently. I believe this recurring issue represents a known vulnerability that could potentially expose Hyundai and its dealerships to liability should an owner suffer harm while addressing this malfunction. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Reported this previously, but more information was gathered, thanks to collision mechanic who guessed immediately when he heard 2023 hybrid Sonata - he said "they're notorious for it." Was at a stand still in a parking space/lot I know well. Cautious driver, watch my speed, very aware of other drivers, quick reaction time. Incident mid day, no pedestrians, distractions, no moving traffic. Vehicle doors shut, seat belt on. Not on incline. Pulled into parking spot I use weekly, spot has parking curb. Was at a full stop. Realized I had not pulled into the spot quite far enough, and attempted to inch vehicle forward. (Do not recall any warning lights, but this car usually alerts at literally anything - even shadows.) Very lightly applied gas to inch forward, slowly. Felt slight "scrape" of undercarriage on the parking curb. Put car in reverse, lightly applied gas to inch back. Car did not rev, no screeching tires, it was at a standstill previously. Was in Eco mode. All seemed normal, until vehicle suddenly launched UP the parking curb, full force, and into a building pillar directly ahead. The car never moves with that much force, I'm not a pedal-to-the metal driver. Eco mode on. No airbag deployment, injuries, etc. Sheriff took report for the building, simple incident. I couldn't make sense of it. I know how overly cautious I am while parking, what I do, and don't do. Took responsibility, but was still analyzing a week later, and explained what I remembered to the mechanic. He guessed right away. Said Sonatas were notorious for it. He said they're known for randomly applying the ebrake unexpectedly - and also randomly releasing the ebrake - and aggressively (and silently) switching from electric to gas when met with resistance, aka the parking curb. Insurance totalled the car. 2.5 years old, 17k miles. This was my 3rd Hyundai in 20 years, others were great. Discovered 40,000 Elantra hybrids, same year as my Sonata, were recalled due to "unintended acceleration."