2018 Hyundai Sonata Fuel system Problems

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.

NHTSA ID

11752670

Incident

May 11, 2026

Mileage

92,000 mi

Fuel line leak, car is parked, fire hazard, a mechanic has been there to inspect

NHTSA ID

11749020

Incident

Jul 7, 2026

Engine blown out malfunction took two dealer Hyundai Folsom Lake stated rings are bad sludge buildup in engine and stayed at Hyundai motor America denied engine replacement due to knowledge under Theta two engine extended warranty settlement of 150,000 MI 15 years I'm still within warranty but are still being denied had numerous of issues with vehicle oil consumption knock knock sensor replace and other maintenance done since purchase vehicle brand new in 2018

NHTSA ID

11737468

Incident

Apr 4, 2026

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 condition has deteriorated further, requiring replacement of fouled spark plugs every 350-500 miles. Loss of power and engine shaking can occur at any time, presenting a safety hazard for me and other drivers.

NHTSA ID

11736185

Incident

Sep 23, 2024

Throttle response intermittent problem no acceleration since new. No codes available. When entering traffic engine stall factor flat spot. Been to dealer many times (Bud Clary) and just recently (04/26) confirmed the fuel pump is the problem. Unable to confirm because of no "codes". Will not replace or register for recall without proper codes. No check engine lamp. No inspection by police or insurance only the dealership service department is aware of the problem.

NHTSA ID

11732817

Incident

Jan 28, 2018

Had an oil change, then 2 weeks later car making noise, checked the oil and it was completely empty, so we refilled the oil. Then a month after again same issue no oil, refilled it again and now a week later it's 2 quarts low already. Also when I come to a complete stop when it is time to go again it's very slow at going or if I try to excel it takes it a very long time to actually excel I think something's wrong with the fuel pump

NHTSA ID

11728690

Incident

Mar 2, 2026

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. Despite this, no written diagnostic findings or repair determination have been provided. The issue has been persistent, progressive, and reproducible, and represents a potential defect affecting engine integrity and safe operation of the vehicle.

NHTSA ID

11726107

Incident

Jan 31, 2026

I bought a 2018 Hyundai Sonata a few years back. No warranty. Used. 110,000 miles. A few short months after I purchased it, it stopped working. I took it back to the same dealership where I purchased it and they said they had to replace the coil packs and spark plugs and clean something in the engine out because there's a defect in the engine. I paid $500. Fast forward a few months later. Same thing happens. I take it to an auto repair shop because it's cheaper and the mechanic says he deals with these same issues with other customers who have similar year, make, and models. This pattern continues to this very day. It broke down while I was working my 2nd job. I have a daughter. She plays sports. I have a second job. I need this problem completely alleviated as quickly as possible. Like a lot of the American public, I don't have extra money to keep up with anything beyond the normal maintenance of my vehicle. I keep it up to date with all oil changes. What can you do to get me a vehicle I can trust and it not break down every couple months and cost $300-$600 each time? I don't have good credit (I'm working on that) I have medical issues that I have to visit my doctor for every 3 months. I have the loan through Capital One and they don't offer refinancing. My father who has passed was a car salesman his entire career. I just need reliable transportation and if it's a motor problem like they say then I shouldn't be liable to fix it. The manufacturer should. Please let me know if you need any service records from me. Oh and I also have to put about $20 worth of oil in it every week or so between oil changes. My local oil change guys unfortunately know me very well.

NHTSA ID

11726097

Incident

Mar 21, 2026

While driving on the highway, my 2018 Hyundai Sonata experienced sudden loss of engine power and became undrivable. The failure occurred without warning at approximately 86,500 miles. At the time of the incident, there were two children in the vehicle, and the breakdown occurred at night in cold temperatures (approximately 20°F). An authorized Hyundai dealership later diagnosed zero compression in cylinder 3 and confirmed a cracked piston, recommending full engine replacement. The sudden loss of power while driving created a safety risk due to traffic conditions and environmental exposure.

NHTSA ID

11705457

Incident

Nov 27, 2025

I am submitting a formal complaint regarding ongoing and severe engine issues with my 2018 Hyundai Sonata SE. Despite proper maintenance, the vehicle has developed extreme oil consumption and misfire problems that have made the car unreliable, unsafe, and financially burdensome. Beginning around 118,000 miles, the vehicle started consuming oil so rapidly that I was forced to completely replace the oil every 1–2 weeks because it would run dangerously low or nearly empty. This level of oil loss is not normal, acceptable, or sustainable. I have detailed documentation, receipts, mileage logs, and maintenance history supporting this. In addition to oil consumption, the vehicle has repeatedly misfired, produced diagnostic trouble codes, and fouled spark plugs with oil. I have been forced to replace spark plugs approximately every two weeks, which is clearly abnormal for any modern vehicle. On multiple occasions, the vehicle has experienced violent knocking noises, severe loss of power, hesitation during acceleration, and near-stalling. One incident was so loud and aggressive that it felt like the engine was going to come out of the hood. These symptoms pose a serious safety risk while driving. I brought the car to a Hyundai dealership at approximately 118,000 miles for an oil-consumption test. The vehicle failed that test, clearly confirming excessive oil consumption. Despite this, Hyundai refused to provide repair, internal engine cleaning, or engine replacement, claiming the vehicle was already over 100,000 miles I have maintained this vehicle responsibly and have documentation of regular oil changes, spark-plug replacements, inspections, and diagnostic reports. Despite my efforts, the issue continues to worsen, and the vehicle remains unsafe and unreliable. This ongoing problem has caused significant financial strain, emotional stress, lost time, and fear of engine failure while driving. Based on countless similar complaints from other Hyundai owners, this appear

NHTSA ID

11700980

Incident

Jul 1, 2025

Unknown. 2018 Hyundai Sonata engine has failed. Only purchased the vehicle in December 2024, and the engine is defective. There is much information, via research, indicating that Hyundai is aware of the engine issues with this year vehicle, but are unwilling to make amends. Vehicle has 100,189 miles.

NHTSA ID

11697623

Incident

Oct 1, 2025

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.

NHTSA ID

11689709

Incident

May 24, 2025

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. My VIN does not fall under the current extended warranty, but the issues are identical to the issues of the VINs that do fall under the extended warranty.

NHTSA ID

11679080

Incident

Jul 16, 2025

Urgent Complaint About Repeated Engine Issues on 2018 Hyundai Sonata (VIN: [XXX] ) Hello, I’m writing to file a formal complaint regarding a 2018 Hyundai Sonata, VIN [XXX] , 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. This has caused severe financial hardship for my family, who still have to pay nearly $10,000 on a loan for a failing vehicle. I am requesting Hyundai to investigate whether this vehicle qualifies for: •An engine recall, hidden warranty, or class action settlement •A buyback or goodwill repair INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ID

11678903

Incident

Feb 8, 2023

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.

NHTSA ID

11678701

Incident

Aug 6, 2025

Mileage

72,000 mi

The engine shuts off, doesn’t start, check engine light flashing, losses power, jerks while driving it, i will get it up yo speed then will shut off or won’t move.

NHTSA ID

11671246

Incident

Jan 2, 2025

Multiple critical mechanical and safety issues have occurred with my 2018 Hyundai Sonata Sport. The vehicle has experienced persistent engine misfire, a severe oil leak, emissions system failure, and extensive paint deterioration. A certified technician confirmed an active oil pan leak with no dashboard warning lights, posing a fire and stalling hazard. To prevent further damage, I replaced the entire oil pan and spark plugs at a personal cost of approximately $800 at Firestone Complete Auto Care. The check engine light revealed diagnostic code P0420 – Catalyst System Efficiency Below Threshold (Bank 1). An O’Reilly emissions scan confirmed the catalytic converter failure, and emissions status was marked “RED.” The vehicle will not pass an OBD-based emissions test. At 149,219 miles, Hyundai refused warranty coverage due to mileage. A certified Hyundai dealership quoted $3,722 to replace both the catalytic converter and valve cover gasket, which remains unaffordable and unrepaired. In addition, the factory-applied white paint began peeling severely from the hood and roof. Although Hyundai issued a warranty extension for this known defect, the dealership refused to repaint the hood, citing a minor dent — even though the peeling is clearly unrelated. The exposed metal has started to rust, risking structural deterioration. All concerns have been evaluated by certified Hyundai service and independent professionals. These combined mechanical, emissions, and exterior failures raise serious safety and durability concerns. I am filing this report to document manufacturer-related defects that may affect other owners of this model and year.

NHTSA ID

11664986

Incident

May 23, 2025

Burns oil fast. 900 miles from an oil change the car oil stick was empty. There are no signs of oil leaking. Every 1000 miles you have to place oil back into it. I’m not the only one complains of this issue. I was reading on Reddit and it’s thousands of people having the same issue.

NHTSA ID

11662951

Incident

May 1, 2025

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.

NHTSA ID

11651132

Incident

Mar 20, 2025

- Component or system that failed: engine (cylinder #4 misfire) - Safety was put at risk twice: once when knock sensor went off on interstate (October) and engine went into limp mode (aka protection mode). Required a tow from the, which was tricky with a vehicle full of passengers. Safety was put at risk gain when vehicle began to stutter/sputter on interstate (December). Drove 4-cylinder vehicle essentially on three cylinders an hour to dealership - Problem has been confirmed by dealer (Southern States Hyundai, Raleigh, NC) - vehicle has been inspected by warranty inspector, who requests approval before disassembling engine to diagnose issue. However, based upon maintenance records and manufacturer's history of engine issues (more on this below), owner should not be liable for investigating a well known issue. At the time of this writing, the issue has been escalated beyond the dealership and warranty to Hyundai Motor America, and currently awaiting the results of their findings. - symptoms of the problem include constant oil leak from vehicle purchase in May 2024 up to engine failure in December 2024. Various temporary remedies (oil changes and repairs, including oil drain plug gasket replacement, crush washer replacement, and replacement of cracked oil pan) did not fix the issue. Additionally, in the October incident, Hyundai dealership (Sport Durst Hyundai, Durham, NC) simply updated the knock sensor detection (KDS) software, despite the vehicle previously receiving the update in 2019 (this can be verified). Finally, owner, noted "engine knocking" (aka 'tapping') in vehicle prior to engine failure. - Hyundai (the manufacturer) settled a class action lawsuit in 2021. Vehicle is one of the vehicles listed under Class Vehicles, but dealer, nor warranty company, nor Hyundai seem to want to resolve issue, which both alienates owner and presents a safety hazard, as the vehicle is unsafe to drive. All claims here will be supposed via documentation and images.

NHTSA ID

11633308

Incident

Dec 18, 2024

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.

NHTSA ID

11586305

Incident

Apr 5, 2024

I own a 2018 Hyundai Sonata 2.0 turbo I paid cash for it in [XXX] with 2011 miles on it for 24,000 cash didn’t start having problems until 2022 then the I kept hearing a knocking on the left front wheel. I had it look at several places because the Hyundai of Louisville dealership kept telling me my title was branded I didn’t know what that meant till I took my title to the tag office and had the sheriffs department check the title out and it was an still is 100 % clean then my engine kept getting worse an in may of 2023 the engine stopped working I had the car towed to the local dealership and they couldn’t even look at it till Aug of 2023 the they told me I shot out a code 99 and they refused to update my software for the knock sensor system and wouldn’t honor the regular 60,000 miles warranty my car only had 48,000 miles on it . They didn’t bother telling me about the faulty GDI 2.0 turbo engine in August of 2023 I had to research it and find out on the internet that it’s a excessive oil consumption problem with this faulty engine. I had my car stolen for 6 days in April of 2023 and everything was taken out of my glove box an trunk . My oil change receipts were kept in an envelope in the glove box and were stolen with all my car registration an insurance papers . So the dealership refused my free engine replacement because I don’t have all my oil change receipts and blamed me for the oil being out of the engine which is due to the faulty GDI 2.0 turbo engine the dealership has now had my car 300 days I’ve been walking to and from my work I can’t afford a new engine all I want is me free engine replacement I have all the articles printed of all the engine problem with the cars catching on fire or just stop running period . I need some representation on having the Hyundai of Louisville Kentucky on Dixie highway to get me my free engine replacement they want 14,000$ for a new engine. I’m extremely mad and frustrated with this entire situation I have retained a lawyer. INFORMATION REDACTED PURSUANT TO THE FREEDOM O

NHTSA ID

11577822

Incident

Jun 23, 2023

The car was sitting in the parking lot and randomly black smoke started coming from it and then it turned into fire within in minutes. No one was in the vehicle and 911 was contacted.

NHTSA ID

11573805

Incident

Feb 6, 2024

Mileage

183,000 mi

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 .

NHTSA ID

11536537

Incident

May 23, 2023

Mileage

127,961 mi

Fuel pump started going out. My brothers vehicle also started going out too in the same vehicle as this. It's clearly a wide issue. Car stalls when gas is at half tank.

NHTSA ID

11514044

Incident

Jan 7, 2023