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 operating the vehicle, there was an abnormal fuel odor inside the vehicle. The vehicle was taken to the local dealer and was diagnosed with an inoperable low-pressure fuel pump. The contact was informed that the low-pressure fuel pump needed to be replaced. The vehicle was not yet repaired. The manufacturer was notified of the failure. The contact stated that the manufacturer had issued an extended warranty coverage for the failure. The failure mileage was 92,000.
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.
Car consumes TOO much oil. Even after I get an oil change I have to add more oil weeks later and the oil is always black. Several times the sensor has gone out on me on the hwy and I'm not able to accelerate or go over 35 miles which is extremely dangerous .
Urgent Complaint About Repeated Engine Issues on 2018 Hyundai Sonata (VIN: [redacted] ) Hello, I'm writing to file a formal complaint regarding a 2018 Hyundai Sonata, VIN [redacted] , currently financed and still owing $9,700, but the vehicle is no longer reliable or functional. For over a year, the car has had constant mechanical issues, primarily: Spark plug failures within weeks of replacement Repeated misfiring Constant oil consumption - requiring oil refills every few days No clear cause ever detected by diagnostic machines Despite replacing the top engine cover, spark plugs, filters, and performing other repairs, the car continues to break down and remains unsafe to drive. These issues began shortly after the 2-year warranty expired in 2023, and have escalated rapidly. …
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. …
I am submitting this complaint to report a serious and ongoing safety defect involving the engine of my 2018 Hyundai Sonata Sport equipped with the 2.4L Theta II engine. The vehicle has been officially tested and documented by Hyundai as consuming more than two (2) quarts of engine oil per 1,000 miles, which Hyundai has acknowledged following completion of its oil consumption test procedure. Despite this confirmation, Hyundai has declined to fully correct the defect. As the condition has progressed, the engine now fouls spark plugs every 350-500 miles, resulting in: Engine misfires Loss of power during operation Rough running and hesitation Risk of sudden engine stalls while driving This condition occurs without warning and requires repeated roadside or emergency repairs simply to keep the vehicle operable. …
The fuel pump filter housing is the cause of the malfunction, it is available for inspection upon request. When I am driving I intermittently lose fuel delivery altogether and my car comes to a halt for a second until I press on the gas pedal to get the car going again, this puts myself and other people in danger if my car randomly stops while I am driving around others and causes crash risk. An independent service center ran a diagnostic and stated it was the fuel pump filter housing. It has not been inspected by the manufacturer, police, or insurance reps. But it has been inspected by the service center near me. An engine code was produced that pointed to the gas cap, but the gas cap was fine, which indicates fuel delivery issues. There was also shaking during acceleration prior to the incident happening. …
Oil consumption was ridiculously high, changing oil/topping off oil constantly. Car would not accelerate over 30 mph without sputtering and rumbling. I had mechanic diagnose bad sparks plugs due to sitting in oil from leaking. After I had them repaired/replaced the car drove great for 1 day, then decided to die in the middle of a busy intersection while I had my teenage son in the car with me. My son and I had to PUSH it out of the busy intersection onto a side street to get out of the way! I had it towed to Hyundai dealer who said the spark plugs were bad and that the fuel pressure sensor and gdi pump were faulty and needed replacement. Left front lower control arm/ball joint assembly also requires fix. To the tune of $3000 + . It's been at dealer for past few months until I can afford the repairs including the 2nd diagnostic and tow it took to get it to dealership.
The motor blew in my 2018 Hyundai sonata due to a manufacturing defect. There was a recall on it a couple of years ago. They acknowledged it was a defect which is why they put an extended warranty on the engine. Because I could not come up with maintenance records dating back until 2018 (I only had them dating back to 2020), they denied my motor and will not fix it. I bought the car brand new in 2018 and have had nothing but issues ever since. I have had to change the oil in this vehicle every 2 weeks, because it would be nothing in the oil tank at all. When the recall come out, they said they could not fix the vehicle until the motor was blown. Now that the motor has blew, they won't fix it because I don't have repair records dating back 6 years ago.
My 2018 Hyundai Sonata (approx. 60,000 miles) began consuming excessive oil, and the engine started smoking while driving. My wife barely made it to the dealership - the car was unsafe, struggled to stay running, and visibly smoked from under the hood. Hyundai acknowledged the oil issue but refused to cover engine replacement. Instead, they approved a one-time combustion chamber cleaning and requested we drive the car 1,000 miles to "see if it gets better." This is a major safety concern. The vehicle is part of a group of Hyundai models known to have defective Theta II engines that have led to engine failure, fire risk, and recalls. This issue is widespread, and Hyundai is not taking proper responsibility for defective engines in cars like mine.
Fuel System complaints in other Sonata years
Frequently asked questions
How common are fuel system problems on the 2018 Hyundai Sonata?
NHTSA has 33 complaints about the fuel & propulsion system of the 2018 Hyundai Sonata, 9% of the model year's 374 complaints.
Is there a recall for 2018 Hyundai Sonata fuel system problems?
No. NHTSA lists no fuel & propulsion system 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 fuel system problems start?
Half of the complaints with a recorded mileage happened before about 92,000 miles, and 29% before 25,000 miles.
Is it dangerous?
Owners linked 0 crashes, 1 fire and 0 injuries to fuel & propulsion system 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.