2023 HYUNDAI Sonata

My car was having an issue where it was losing all the coolant, causing my engine to overheat twice while driving down the highway. Unfortunately I couldn't find a leak anywhere and there was no fluid leaking in my garage. I lost an entire reservoir of coolant overnight. After taking my car to the dealership to get repaired, I was told that it was leaking my coolant into the exhaust system and burning it up. I was also told "it was a know issue, they had a bulletin from Hyundai on how to fix the problem, and Hyundai completely redesigned the part to stop the leak and it had to be special ordered." I was without my car for a week and left with a $1300 bill as apparently it was not covered by my warranty. I have no idea how a known issue is happening so frequently that requires a nationwide bulletin and a part redesign, yet somehow is recalled. Especially considering it left me stranded on the side on the side of the highway in Indiana during a snow storm but someone seriously needs to investigate it.

I am reporting a serious coolant system defect on my 2023 Hyundai Sonata Hybrid with about 13,500 miles. The vehicle develops an internal coolant leak while driving. Coolant burns off and white steam/smoke comes out of the exhaust, especially during acceleration. When this happens, the coolant level drops quickly, the interior heater stops working, and the car soon displays an engine overheating warning, forcing me to stop driving. This has happened multiple times and makes the vehicle unsafe. When I checked under the hood, coolant was at a low/empty level after overheating events. The car becomes undriveable once the alarm appears. I took the vehicle to a Hyundai dealer, and even though the vehicle is only 2 years old, they told me it was “out of warranty.” I had to pay about $1,500 for repairs, and since the dealer refused a loaner, I paid $250 for a rental car. I called Hyundai USA on 9/13/2025 and opened Case Number XXX. Hyundai acknowledged they are aware of coolant issues on the Sonata Hybrid but said no recall exists. This issue appears widespread. Many other owners report the same symptoms: white exhaust steam, coolant smell, coolant loss, no interior heat, and engine overheating. Hyundai released TSB 23-EM-009H, describing a failure where coolant leaks internally in the Exhaust Heat Recovery System (EHRS), causing white smoke and overheating—matching my symptoms exactly. This defect is a safety hazard because overheating can occur suddenly while driving, risking engine damage or breakdown in traffic. I request NHTSA investigate this issue as a potential recall-level defect on the 2023 Sonata Hybrid. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filled gas tank up on Friday [XXX] about 10am as leaving Boca Raton, FL to head North to New Port Richey, FL. About 30 minutes later the gas mileage said there was only 90 miles left in the tank. Stopped at the next gas station to make sure nothing was leaking, added a little more until it clicked, basically full again. Got to approximately [XXX] near Morris Bridge in Tampa area, the car started to decelerate and then all the engine lights came on and car was shutting off, was able to pull to the left side of the road and Looked into the back seat noticed the back seat was rising. Looked under the back of the car and the frame looked like it was pushing up into the backend of the car. DOT was called out to the scene as it appeared the car could have exploded. This could have killed my [XXX] daughter (which was who was driving the car) or other people on the road. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Coming home from work I stopped at a red light and when I tried to accelerate the vehicle was surging and jerking shaking and wouldn't pick up speed 2 min later the check engine light appeared flashing thankfully I was 5 min from home got the car towed the next morning to hyundai dealership said it was an cylinder misfire the car only has 30,000 miles on it