Mileage when the problem started
Owner reports
Selected complaints filed with NHTSA by 2018 Hyundai Sonata owners, lightly cleaned up (personal details are redacted by NHTSA).
The contact owns a 2018 Hyundai Sonata. The contact stated that while driving approximately 60 MPH the vehicle suddenly began sputtering and then completely stalled. The contact had to coast to the side of the road and noticed the check engine light illuminated. After approximately 10 minutes, the vehicle was able to restart. When starting the vehicle there would be a sputtering followed by the vehicle shutting off. The failure began to occur while idle as well. The contact stated that while attempting to reverse out of a parking spot the vehicle suddenly accelerated forward instead. As a result, the vehicle ended up crashing into a concrete light post. The air bags did not deploy. There were no injuries or medical attention needed. The vehicle was able to be driven after. No police report was filed. …
Unknown what system failed. The vehicle is at an impound lot and can be inspected on request. Police and fire department were on the scene. Police did provide a report # , and fire department provided a fire rescue case number. Safety of driver was put at risk due to the fire and potential for burning or even death. Other drivers could have been at risk if traffic had not allowed for quick movement to side of the road. No warning lamps had been on prior to the drive and none prior to fire. First indication was a burning smell while driving. As pulling over, another driver honked to alert to fire he could see from rear of ca,. before I noticed the flames. Upon getting out of car first flames I saw appeared to be coming from under passenger side of car. The fire department arrived about 15 minutes after pulling to side of the road. The car was fully engulfed in flames. …
The vehicle had safety and mechanical problems shortly after purchase, even with low mileage. The issues included warning lights, abnormal noises, repeated mechanical failures, and poor performance that affected the safe operation of the vehicle. These problems started early and continued over time despite repairs and maintenance. Before the incident, the vehicle showed signs of malfunction, including instability while driving and loss of normal performance. These symptoms created an unsafe driving condition and increased the risk of a crash. I believe the vehicle had defects from the beginning that affected safety. The failure contributed to the accident that occurred while driving on the highway, putting my life and my family at risk.
The contact owns a 2018 Hyundai Sonata. The contact stated while driving 70 MPH, the vehicle went into LIMP Mode and lost motive power. The contact was able to pull to the side of the roadway, where the vehicle failed to restart. The check engine warning light was illuminated. The vehicle was towed to an independent mechanic, who determined that cylinder #1 was misfiring on every cycle due to damage to the piston. The vehicle was not repaired. The manufacturer was not notified of the failure. The failure mileage was 107,000.
The contact owns a 2018 Hyundai Sonata. The contact stated while driving 70 mph, he heard an abnormal noise, and the vehicle began to vibrate. The contact stated no warning light was illuminated. The contact was able to park the vehicle at a nearby parking lot. The vehicle was not drivable. The contact towed the vehicle to the local dealer. The vehicle was not diagnosed or repaired. The manufacturer had been informed of the failure. The failure mileage was approximately 50,000.
The contact owned a 2018 Hyundai Sonata. The contact stated that while driving at an undisclosed speed, the vehicle sputtered, jerked, and lost motive power. The check engine warning light was illuminated. The vehicle was able to restart but made an abnormal ticking sound. The vehicle was taken to the dealer but was not diagnosed or repaired. The manufacturer was not made aware of the failure. The failure mileage was approximately 72,000.
The contact The contact stated that when taken the vehicle for a service campaign repair and shortly after went for recall r The vehicle does not run properly on cold starts, the RPMs increase rapidly and slow down, vehicle jerks forward once beginning to drive.. The vehicle does not have this issue once the vehicle is warm. The manufacturer was not notified of the issue. The approximate. Failure mileage was 47,575.
Following completion of Service Campaign 9C2 (ECU software update, TSB 25-01-087H) at a Hyundai dealership, my 2018 Sonata immediately exhibited drivability changes that were not present before the service. Symptoms include altered shift timing, hesitation, and rougher throttle response - particularly noticeable during the first several minutes of driving. These symptoms began on the first drive after the recall update was applied and have been consistent since. The vehicle was returned to the dealership for inspection. No underlying mechanical issue was found, confirming the drivability change is directly attributable to the ECU software update. The vehicle has been maintained strictly per Hyundai's manufacturer-recommended schedule and had no prior drivability issues. …
My car is misfiring, hesitating accelerating, severely shaking and vibrating which you can feel in the pedals and steering wheel, and the check engine light is on. This issue has been ongoing for over a week already. When the engine light first came on on 9/7, i pulled over on the side of the road and had a mobile mechanic check it out. The code was coming up as a bad ignition coil in cylinder 1. When he took out the coil and spark plugs, he saw scoring on the spark plug from oil as well as oil being consumed in the cylinder itself which has been causing my vehicle to misfire. The mobile mechanic stated on his invoice that I need a new engine. I took my car to Faulkner Hyundai on 9/11 and they said the best they can do is an oil consumption test even though they personally know I need an engine as well. …
The vehicle developed a progressive engine failure beginning in early 2024, including loud knocking noises at cold start and visible white/gray/black exhaust smoke. The condition worsened over time. In February 2026, the failure escalated to active oil discharge from the exhaust pipe while the engine was running. Oil exiting through the exhaust indicates internal engine failure (such as piston rings, cylinder walls, or valve seal failure), not an external leak. This creates a safety risk including potential loss of power while driving, risk of engine seizure, and possible fire hazard due to oil in the exhaust system. The condition has been documented on video multiple times and was shown to dealership personnel. The vehicle was taken to a Hyundai dealership for evaluation and remains available for inspection. …
Transmission complaints in other Sonata years
Frequently asked questions
How common are transmission problems on the 2018 Hyundai Sonata?
NHTSA has 40 complaints about the transmission & drivetrain of the 2018 Hyundai Sonata, 11% of the model year's 374 complaints.
Is there a recall for 2018 Hyundai Sonata transmission problems?
No. NHTSA lists no transmission & drivetrain recall for the 2018 Hyundai Sonata, though it has 1 recall for other components. If the problem is widespread, a repair may still be covered by an extended warranty or a manufacturer service bulletin — ask a dealer.
At what mileage do 2018 Hyundai Sonata transmission problems start?
Half of the complaints with a recorded mileage happened before about 48,000 miles, and 33% before 25,000 miles.
Is it dangerous?
Owners linked 2 crashes, 1 fire and 1 injury to transmission & drivetrain problems on this model year. If you notice symptoms, have the car checked before driving further.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) — owner complaints through October 20, 2026, recalls and defect investigations; fuel economy from the EPA. Complaints are unverified reports and are not proof of a defect. How we rate model years.