5,099 of the
22,259 complaints filed about the Hyundai Sonata
are about the engine —
23% of everything owners reported.
The worst model year for it is 2011.
The vehicle suffered an abrupt, internal engine seizure while operating in active traffic at highway speeds. This sudden loss of power created an immediate crash hazard, as the vehicle decelerated rapidly in the travel lane, narrowly avoiding a rear-end collision and putting my family and other motorists at extreme risk. The vehicle was towed immediately to an authorized Hyundai dealership service center where it is currently awaiting the physical recall inspection. Prior to the complete engine failure, there were no warning lights, abnormal gauge readings, dashboard messages, or noticeable performance symptoms. The engine seized completely without warning. The vehicle has an open, uncompleted Federal Safety Recall 162 (NHTSA Campaign Number: 16V729000) for this exact engine manufacturing defect and bearing failure.
NHTSA complaint #11758160 — an unverified report by a vehicle owner.
The vehicle suffered an internal connecting rod bearing failure, a known manufacturing defect affecting the Theta II GDI engine. The failure was explicitly diagnosed via the manufacturer - specific OBD-II fault code p1326 Knock Sensor Detector System. This defect causes sudden engine stalling poses an immediate risk of catastrophic engine failure or fire while driving. Hyundai Motor America has denied financial reimbursement for the required engine repair because the work was completed by an independent shop and third-party arbitration deadline (BBB Auto Line) communicated to me. The manufacturer is actively refusing to remedy an acknowledged safety defect.
NHTSA complaint #11757692 — an unverified report by a vehicle owner.
The oil is low, went to get looked at by another mechanic besides Dealer cause they want to hit you over the head with prices. Was told car burning oil. Took to dealer for Oil Consumption Test. Had to pay for oil change. Came back a little before 1,000 miles and car failed. They charging me 900.00 for next step because I can’t find ALL the oil changes. I just don’t get it, if this is a known issue with this model engine why do I have to pay.
NHTSA complaint #11757665 — an unverified report by a vehicle owner.
The contact owns a 2019 Hyundai Sonata. The contact stated that while driving at an undisclosed speed, the vehicle experienced severe overheating and excessive oil consumption. The contact also stated that there was a misfire in the engine even though the spark plugs and ignition coils were replaced. Due to the failure, the vehicle could not be driven with the air conditioning activated. Additionally, the engine was knocking and shaking abnormally, causing an oil leak and a smoke odor due to the oil burning. The vehicle was taken to a dealer, where an engine replacement was recommended. The vehicle was not repaired. The manufacturer was notified of the failure. The failure mileage was 140,000.
NHTSA complaint #11757693 — an unverified report by a vehicle owner.
I recently had the 9C2 Emissions recall update performed on my car, and since the update my car drives like total garbage after a cold start. It hesitates to accelerate, it bucks when trying to accelerate, and it’s to the point the engine is about to stall. I took it back to the Hyundai dealership and they said they are aware of the issue, but there is no fix from Hyundai at this time. This is a major safety concern, as the car barely wants to accelerate after a cold start. Please have Hyundai fix this safety issue.
NHTSA complaint #11757253 — an unverified report by a vehicle owner.
The paint on all parts of the car is completely coming off down to bare metal. It’s as if the car wasn’t prepped to receive paint. Every Hyundai I pass that’s white the paint is coming off. There is also an internal engine oil leak where I’m losing 4qts of oil a week.
NHTSA complaint #11757263 — an unverified report by a vehicle owner.
MY ENGINE WAS DECREASING IN SPEED AND SHUTTING OFF IF I BRAKE TO SLOW DOWN ON MAJOR EXRESSWAYS AND LOCAL ROADS. I WAS ADVISE BY MY DEALERSHIP MECHANIC SHOP THAT MY ENGINE HAD A RECALL AND NEED TO HAVE IT TOWED TO A HYUNDAI SERVICE DEALER FOR A REPLACEMENT ENGINE . MY ENGINE LIGHT ON THE DASHBOARD HAD A CONSTANT BLINKING LIGHT. MY VEHICLE WAS INSPECTED CAMELBACK HYUNDAI AND A NEW ENGINE WAS REPLACED. THE DEALERSHIP IS HOLDING MY VEHICLE HOSTAGE DEMANDING I PAY 2500.00 FOR REPLACEMENT ENGINE THAT WAS A RECALL. THEY ARE THREATENING TO PLACE AN ABANDONMENT CHARGE AGAINST ME
NHTSA complaint #11756752 — an unverified report by a vehicle owner.
On January 26, 2026, my 2019 Hyundai Sonata SEL suddenly became inoperable overnight. The vehicle had been operating normally with no warning signs—no check-engine or oil-pressure light, abnormal engine noise, overheating, loss of power, or other indication of an impending failure. The following morning, the engine would not start. The vehicle was towed to an independent mechanic on January 28, 2026, who determined that the engine was locked/seized. On February 11, 2026, it was towed to Wayne Hyundai for further diagnosis. The vehicle had only 51,533 miles and had received Hyundai’s Knock Sensor Detection System (KSDS) update. Hyundai denied warranty coverage, citing engine sludge, despite my providing a complete service history after resubmiting the missing receipts I had previously misplaced. My primary concern is safety, not the warranty dispute. A sudden engine seizure without warning could cause an unexpected loss of propulsion or create a dangerous situation if the engine fails while the vehicle is being driven. This concerns me because Hyundai Theta II engines have previously been associated with engine seizure and stalling, including issues addressed through The Hyundai Theta II Engine Settlement: and subsequent litigation involving certain 2019 Sonata vehicles. I respectfully request that NHTSA investigate whether a continuing or insufficiently addressed engine defect exists in affected 2019 Hyundai Sonata vehicles, particularly sudden engine seizure/no-start failures occurring without warning. I also ask NHTSA to examine whether existing recalls, campaigns, software updates, warranty extensions, and other remedies adequately protect owners when an engine fails suddenly before the KSDS system provides a warning.
NHTSA complaint #11756831 — an unverified report by a vehicle owner.
Excessive oil consumption. I lose 3 qt of oil every 1200 miles. I have had the required maintenance on the car and still having excessive oil consumption.
NHTSA complaint #11756370 — an unverified report by a vehicle owner.
My Sonata 2016 suddenly lit up the Check Engine icon, which was blinking. It is available for inspection request, as it's in the shop right now. Added 2 qts of oil just to be safe. Was hoping the light would go away in the morning. It didn't. The car was sputtering and jerking while I was attempting to get where I was going, so I drove a little slower so it wouldn't stall out, which would have caused someone behind me to crash into me if it stopped suddenly. My mechanic said it was engine failure, possibly due to oil burning. Hyundai Dealer told me there is no recall for this issue, but my mechanic said there had been. I was never notified of such, and when I called them, they said that there was no recall, and she acted like she had never heard of the problem. I find that amazing, since on your website, there are some 717 claims of the same problem.
NHTSA complaint #11756308 — an unverified report by a vehicle owner.
The contact owns a 2015 Hyundai Sonata. The contact stated that while driving on several occasions at various speeds, the vehicle lost power, and the check engine warning light was illuminated. The vehicle was taken to a dealer where it was diagnosed that the engine had failed and needed to be replaced. The vehicle was repaired, but the failure reoccurred within a year. The vehicle was taken back to the same dealer where it was diagnosed and determined that a software update was needed. The vehicle was repaired, but the failure persisted. The vehicle was then taken back to the same dealer, and there was oil on the pistons and a tune-up was needed. The vehicle was repaired, but the failure persisted. The vehicle was taken back to the dealer, where it was advised that an oil consumption test could not be provided until the pistons had failed. The manufacturer was notified of the failure, and a complaint was filed. The failure mileage was approximately 88,000.
NHTSA complaint #11755866 — an unverified report by a vehicle owner.
My Hyundai Sonata engine stalled out while driving on the highway. I had it towed to a dealership with the hope they would fix the issue because it was supposed to be covered under warranty from a recall. The dealership said the engine replacement would be covered as long as they got approval from Hyundai. Hyundai apparently only asked that specific dealership for the service records that they had, didn’t even reach out to me or try to find any other service records on the vehicle and denied the claim for “neglect of maintenance” because that dealership only had records from 0-90,000 miles. The dealership got back to me and told me the news and I told them that I will get all service records from 0 miles to current. I got all those records together and sent them to the dealer. A week later they called and said Hyundai was again going to deny my request because of the same “neglect of maintenance” which isn’t true based on the records I have and they have. I have driven the vehicle less than 10,000 miles and there has been nothing wrong with it. No check engine lights ever and regular oil changes.
NHTSA complaint #11756074 — an unverified report by a vehicle owner.
Vehicle: 2015 Hyundai Sonata VIN: [XXX] Mileage: ~85,000 Description of the Problem: While driving, the vehicle suddenly began producing thick smoke from under the hood without warning. I safely maneuvered to the shoulder to avoid an accident. The engine subsequently seized completely and became inoperable. My mechanic diagnosed this as a known internal manufacturing defect in the Theta II engine (connecting rod bearing failure), a widely documented issue for this model and production year. Oil and coolant levels were confirmed normal with no leaks, ruling out maintenance neglect. I initially paid for an unnecessary starter replacement before this diagnosis was confirmed. This is a serious safety hazard that could cause loss of engine power and control while driving, posing a risk to myself and other drivers on the road. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)
NHTSA complaint #11755594 — an unverified report by a vehicle owner.
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. Because the vehicle has repeatedly lost engine power while being driven, including multiple incidents at interstate highway speeds, I believe this recurring condition presents a serious safety risk. I am reporting these incidents so NHTSA can evaluate whether this may represent a broader safety-related defect affecting this vehicle model. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)
NHTSA complaint #11755422 — an unverified report by a vehicle owner.
Since the 9C2 update on June 24, 2026, my vehicle has not driven the same. I'm experiencing clunky or harsh gear changes at low speeds, especially during stop-and-go driving. When I slow down and then accelerate again, the vehicle sputters or hesitates before responding. While driving at lower speeds, I also feel intermittent skips or small surges, almost like bubbles or brief misfires. These symptoms were not present before the 9C2 update, and they have noticeably affected the drivability of the vehicle. It was suggested the transmission needed time to "relearn" driving patterns, but it has been several weeks with no change
NHTSA complaint #11755188 — an unverified report by a vehicle owner.
My 2016 Hyundai Sonata (VIN: [XXX]) has a serious safety issue involving excessive engine oil consumption. The vehicle loses oil rapidly between changes and requires frequent top‑offs to avoid engine damage. This creates a risk of sudden engine failure while driving. The dealership, South Charlotte Hyundai (10518 Cadillac Street, Pineville, NC 28134), refused to perform Hyundai’s official oil‑consumption test. Instead, they told me to pay $750 for a combustion cleaning and stated it would not fix the underlying problem. They would not document the refusal or provide any testing. I contacted Hyundai Corporate multiple times: • May 21, 2026 – Executive Office complaint submitted • June 3, 2026 – Follow‑up sent • June 29, 2026 – Regional escalation sent My Hyundai case number is XXX. As of XXX Hyundai has not responded to any of my Executive Office or Regional escalations. Only Customer Care replied with a template denial and no investigation. I have been waiting over two months with no action from Hyundai Corporate. I am reporting this because the manufacturer has not addressed a safety‑related defect, the dealership refused required testing, and the vehicle continues to consume oil abnormally. I am requesting NHTSA’s assistance in documenting this defect and Hyundai’s lack of response. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)
NHTSA complaint #11755304 — an unverified report by a vehicle owner.
Engine / Short block assembly / Connecting rod bearing seizure. The engine suffered a sudden, catastrophic seizure while I was actively driving on a steep incline mountain road with a cliff on one side and forest on other. The vehicle experienced an immediate, total loss of motive power, forcing an emergency maneuver onto the shoulder in 5 seconds with no power steering or power brakes, creating an extreme collision hazard on a high-speed incline. The rod bearing melted due to a manufacture defect and could have also possible caught fire in heavy fire country. The fuel pump was also leaking recently and just replaced. They are nearly $1800 for a new pump because of price gauging because they are in "high demand". The Check Engine Light was solid (not flashing) for a thermostat code (P0128) due to extreme internal friction/heat from the failing bearings. There were no flashing KSDS warnings or physical signs of engine overheating. My car was denied a new engine under a Federally Mandated Warranty explicitly stating the exact symptoms of internal engine defect that happened in my car under "owner neglect" even though I have changed my oil regularly and even before the manufacture recommended time frames to do so. I've changed the valve covers, 02 sensors, thermostats, and plenty more on this car than any other car I have ever owned proving I'm actually an exceptional owner. I remained nice to all corporate staff during this process while they denied my car proper care under a Federal Mandate. I bought this car to believe that Hyundai was a superior company in regards to warranties, price, and function as opposed to the more expensive counterparts of the same class. Which in the end has cost me way more, and almost my life. This car is dangerous and the company has done everything in their power to try to cover it up while placing blame on the very consumers that are believing in them to do better.
NHTSA complaint #11755077 — an unverified report by a vehicle owner.
This vehicle is subject to a known Theta II connecting rod bearing defect (Recall 162 / KSDS) and a related class action settlement. On October 2, 2025, the vehicle stalled while entering the highway. It was taken to Ken Garff Hyundai Surprise, and the following day, October 3, 2025, it entered engine protection mode (limp mode) during the dealership's own test drive, the exact behavior the Knock Sensor Detection System is designed to trigger for connecting rod bearing wear. The dealership's own service advisor documented in writing, as early as December 27, 2025, that he did not like how the vehicle ran and drove and wanted to resubmit a warranty claim. Despite this documented concern, on May 5, 2026, the dealership's service manager told Hyundai corporate that nothing was wrong with the vehicle and that it could be picked up. Hyundai corporate maintained that the engine had passed bearing clearance testing on two occasions, October 3, 2025 and May 23, 2026. I was told the vehicle was safe and retrieved it on June 29, 2026, out of necessity after my family's other vehicle was totaled in an accident. Approximately ten days later, the engine failed completely while I was driving with my family in the vehicle. Hyundai's own repair order documented the crankshaft as seized at over 95 lb-ft of torque. Hyundai subsequently approved and completed a full engine replacement. I am filing this report because a vehicle with a documented, known defect and a documented internal safety concern was represented to me as safe to drive, and it failed catastrophically with my family inside it within days of that representation
NHTSA complaint #11754108 — an unverified report by a vehicle owner.
The contact owns a 2012 Hyundai Sonata. The contact stated that while driving at 30 MPH, the check engine warning light illuminated, the engine started knocking, and smoke emitted from under the hood. The contact decelerated to approximately 15 MPH and drove to her nearby residence. Upon inspection, the contact observed green fluid under the hood. The vehicle was towed to an independent mechanic, where it was diagnosed that the engine had failed and the head gasket was blown. The mechanic informed the contact that the engine needed to be replaced. The vehicle was not repaired. The manufacturer was not notified of the failure. The failure mileage was approximately 100,000.
NHTSA complaint #11754020 — an unverified report by a vehicle owner.