2023 Hyundai Sonata engine problems

“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.”

“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.…”

“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…”

“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…”

“Recall 286 my vehicle suffered from this causing heat module failure misfire in cylinder 2 and high pressure in gas tank. Sports Hyundai had previously done a 180 day repair under recall 9b1 for an expanded gas tank after the repair the car suffered from the updated recall 286 . I brang to the dealership 4 times with check engine and misfires and limp mode between 57k and 68k they refused to fix the car under recall 286 and cleared all the codes and continued to make me leave in a unsafe car. On February 14th it sport Hyundais negligence was the direct cause of an auto accident were the car was unable to move out the way because of lack of power /limp mode. I begged them in the final days of me having the car to fix it and saying I didn’t feel safe and they wouldn’t without an extensive amount of money I could not provide . I’m currently filing a claim with Hyundai consumer affairs and the dca in Newark and also my senators office and I have a lawyer also who might help I wish to report this to the NHTSA.”

“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.”