Which parts fail
Components named in complaints (engine, cooling system, oil leaks, timing chain, exhaust).
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 receiving an oil change, the technician advised that the oil level was very low. The contact stated that the low oil warning was intermittently illuminated. The contact was advised to take the vehicle to a dealer to be diagnosed. The contact had taken the vehicle to a local dealer, where an oil consumption test was performed. The contact was advised that the vehicle was operating normally. The contact stated that the low oil warning light was illuminated again. The vehicle was taken back to the same dealer, and the oil level was topped off; another oil consumption test was suggested. The contact researched online and related the failure to a known issue of oil consumption that could lead to engine failure. …
The contact owns a 2018 Hyundai Sonata. The contact stated that while driving at 55 MPH, the vehicle suddenly lost motive power and was unable to accelerate above 60 MPH. The check engine warning light was illuminated. The vehicle was taken to the dealer, who diagnosed a failure with the knock sensor. The vehicle was repaired, but the failure reoccurred. The contact stated that later while driving at an undisclosed speed, the vehicle inadvertently lost all motive power. The contact was able to coast to the shoulder of the roadway, where the vehicle failed to restart. The check engine warning light was illuminated. The vehicle was towed back to the dealer, who diagnosed a failure with the connecting rod bearings. The contact was informed that metal was observed within the engine and that the engine would need to be replaced. The vehicle was not repaired. …
The contact owns a 2018 Hyundai Sonata. The contact stated while driving 70 MPH, the check engine warning light illuminated, and the vehicle lost motive power. The vehicle was taken to the dealer where the dealer performed a compression check. The failure reoccurred. The vehicle was taken back to the dealer and the contact was advised to drive the vehicle until it blew up. In addition, the contact stated that all four seat belts had failed to function as intended. The contact stated that the front driver's side and passenger's side seat belts failed to retract as intended. The contact stated that the seat belts failed to secure the passengers in place. Additionally, the contact stated that the rear seat belts completely failed to retract as needed. The vehicle was not diagnosed or repaired by the independent mechanic or the dealer. …
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 contact owns a 2018 Hyundai Sonata. The contact stated that while driving approximately 60 MPH, the vehicle started to vibrate roughly. The contact felt the vibration in the steering wheel. The check engine warning light was illuminated. The contact slowed down and pulled off the roadway. The contact turned off and restarted the vehicle and was able to shift to drive(D); however, the vehicle was hesitating and failed to accelerate as needed. The contact drove the vehicle to an independent mechanic at speeds no greater than 40 MPH. The mechanic scanned the vehicle and retrieved codes for a misfire in the engine. The mechanic advised the contact to take the vehicle to a dealer for assistance. The vehicle was towed to the local dealer. The vehicle was not yet diagnosed or repaired. The manufacturer was informed of the failure. …
The contact owns a 2018 Hyundai Sonata. The contact stated that after starting the vehicle, the engine oil warning light illuminated intermittently. The contact pulled over to check the engine oil level and discovered that there was no oil in the engine. The vehicle was taken to Midas, and engine oil was added. The vehicle was later taken to another Midas, who found a crack in the engine oil pan. The vehicle was then taken to the dealer, who informed the contact that Midas had overtightened the oil pan during an oil change, so the warranty to repair the vehicle would not be honored. The vehicle was taken back to Midas, and the engine oil pan was replaced. The contact stated that he was currently in litigation with the dealer and the manufacturer. The manufacturer was made aware of the failure. The failure mileage was approximately 99,000. The VIN was unavailable.
The contact's son owned a 2018 Hyundai Sonata. The contact stated while her son was driving at 68 MPH with a passenger in the front passenger seat, he noticed a burning odor and he noticed smoke coming inside the cabin through the AC vents. There was no further information provided. The contact's son pulled into a gas station and saw fire underneath the hood. The contact's son and the passenger immediately exited the vehicle. The contact's son was able to extinguish the fire with the assistance of bystanders who used fire extinguishers. The vehicle was towed to the dealer. The vehicle was not diagnosed or repaired. The vehicle was then repossessed by the auto financing bank. The manufacturer was notified of the failure and informed the contact that they could not assist as the failure was caused by a missing oil cap. The failure mileage was unknown.
The contact owns a 2018 Hyundai Sonata. The contact stated the vehicle had failed to start. On other occasions while driving at various speeds, the vehicle was not running correctly, bucking, lost motive power and stalled. Additionally, the door and trunk failed to lock securely. There were no warning lights illuminated. A signal was sent to the vehicle however, the vehicle failed to respond. The vehicle was towed to the local dealer but the vehicle was not diagnosed or repaired. The vehicle was then towed to an independent mechanic who informed the contact that the fuel pump failed and caused the starter to burn out and drain the battery. The manufacturer was notified of the failure and provided a case number and referred the contact to the local dealer for assistance. The approximate failure mileage was 23,944.
My 2018 Hyundai Sonata caught fire unexpectedly while parked. The engine suddenly began smoking, then the vehicle ignited and was severely damaged. I am still financing the vehicle through Capital One. After researching, I discovered that my vehicle's engine is part of a known Hyundai recall due to fire risk (Theta II engine defect). I had no prior warning or engine-related issues that would have predicted this. I strongly believe the fire was caused by a manufacturing defect, and I'm requesting that NHTSA investigate Hyundai's handling of this issue and ensure victims like myself are compensated - even if not physically injured. I can provide photos, a fire report, and additional documentation if needed. Please let me know the next steps or if I qualify for any related recall recovery programs.
The contact owns a 2018 Hyundai Sonata. The contact stated that while driving, the oil warning light illuminated. The contact stated that he checked the engine oil level and discovered that there was no oil in the engine. The vehicle was taken to the dealer where the failure was diagnosed as an oil plug needing replacement. The vehicle was repaired however, the failure continued. The vehicle was taken back to the dealer several times and the failure cause could not be determined. The contact stated that recently an oil consumption test was completed, and the dealer determined that to be the failure cause. The dealer contacted the manufacturer who stated that the failure cause was due to the owner's negligence and no solution was offered. The approximate failure mileage was 40,000.
NHTSA investigations
Loss of Motive Power
The National Highway Traffic Safety Administration (NHTSA) received a letter dated July 13, 2022, petitioning the Agency to initiate a safety defect investigation into loss of motive power allegations attributed to oil drain pan assembly failures on certain Hyundai Motor America, Inc. and Kia America, Inc. vehicles spanning Model Years (MY) 2005-2021.
Engine complaints in other Sonata years
Frequently asked questions
How common are engine problems on the 2018 Hyundai Sonata?
NHTSA has 224 complaints about the engine & cooling of the 2018 Hyundai Sonata, 60% of the model year's 374 complaints. The component named most often is engine › oil/lubrication › sump/tank (1 mentions).
Is there a recall for 2018 Hyundai Sonata engine problems?
No. NHTSA lists no engine & cooling 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 engine problems start?
Half of the complaints with a recorded mileage happened before about 24,000 miles, and 52% before 25,000 miles.
Is it dangerous?
Owners linked 3 crashes, 8 fires and 2 injuries to engine & cooling 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.