What 758 owners told NHTSA about the 2017 Hyundai Sonata

My engine seemed to be consuming oil way to much I had to do a oil change at 61,000 recommend by tire plus but at 58,000 is when I had to change my oil I also noticed there is a buring smell and its also been leaking oil at times I went to get it checked out by a mechanic at tireplus but they also they are seeing that the oil consumption was not normal and they recommend a possible recall for it because it hazardous for how fast its consuming and the leaks

NHTSA ODI 11748628

Driving home from work on [XXX] (not a safe location)when my car lost power and engine light began to flash. I pulled off to the side of road and called my dad. He came with a code reader and said there was a code P1326. He cleared the code and car drove normally again. 2 days later it began to run rough. I was told about the engine recall so I called Hyundai corporate and told them this same story. I was advised to take to dealership and have the “rod bearings inspected” and shouldn’t matter that my dad cleared the code. The dealership(Massey Hyundai MD) said it had a burnt valve and not part of warranty. But never checked rod bearings. When I called corporate. They said nothing they could do. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ODI 11747509

High oil consumption, burning a quart of oil or more every 500 miles since bought used at Hyundai dealership.

NHTSA ODI 11745870

My 2017 Hyundai Sonata SE, equipped with the Theta II 2.4L GDI engine, is experiencing severe powertrain failures including rhythmic metallic engine knocking, catastrophic oil consumption, and un-commanded surges/jumping in speed while driving. These symptoms manifested following an unauthorized engine replacement performed by Hyundai of El Cajon under Repair Order [XXX], where the dealer covertly outsourced my vehicle to a third-party shop (Legacy Motor Works) to install an unverified used salvage engine block rather than a certified factory assembly. This vehicle is a Class Vehicle under In re: Hyundai and Kia Engine Litigation (Case No. [XXX]), and the KSDS software update (Campaign 953) was successfully completed on my vehicle in 2019. The engine knock, surging, and oil consumption are consistent with the known connecting rod bearing failure defect described in NHTSA investigation PE17-007. The dealership is currently denying warranty coverage, citing a mileage limit that does not exist under my Lifetime Powertrain Warranty, and they are withholding physical documentation of the repair terms. The vehicle is also experiencing secondary safety failures, including a continuous airbag SRS warning light (two years) and electrical shorts caused by the salvage-yard alternator installation, which have destroyed 4 to 5 car batteries. This engine failure represents a significant safety hazard, as the vehicle periodically loses power and surges without driver input. I am requesting that NHTSA investigate this pattern of warranty denial, parts-sourcing fraud, and the safety risks posed by this substandard engine installation. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ODI 11745609

The RED light is lit on the dashboard for the airbag. Unable to use steering wheel electronic features which helps with and was designed for hands free controls. I am unable to cycle through the electronic features or engage the cruise control due to the steering wheel electronics are in-op. Please help and get a recall started. This is not on the consumer.

NHTSA ODI 11743557

[XXX] [XXX] [XXX]; [XXX] [XXX] [XXX] Date: XXX To: National Highway Traffic Safety Administration Office of Defects Investigation (ODI) Subject: Formal Safety Defect Complaint – 2017 Hyundai Sonata Theta II Engine Failure, Excessive Oil Consumption, Intake/Engine Component Failure and Safety Hazard Dear Sir or Madam: I am submitting this formal complaint and request for immediate investigation into the dangerous and ongoing mechanical failures involving my 2017 Hyundai Sonata equipped with the Theta II engine. I believe this vehicle contains a serious manufacturing and/or engineering defect that presents a substantial safety hazard to consumers. My vehicle has experienced a pattern of progressive mechanical failure beginning with abnormal and excessive oil consumption, which appears to be directly associated with malfunctioning engine airflow and intake-related components. Specifically, the lower engine airflow system and intake functionality appear defective, placing excessive strain on the intake manifold system and contributing to cascading engine failures. As a result of these failures, the vehicle has experienced: Severe and excessive oil burning/consumption Intake manifold malfunction and abnormal operating stress Suspected overheating and/or premature head gasket failure Ignition coil failure and electrical shorting/misfires Progressive engine deterioration rendering the vehicle unsafe and unreliable Increased risk of sudden engine shutdown, stalling, fire hazard, or catastrophic engine failure while operating The vehicle has become increasingly unreliable and inoperable due to these conditions. These failures raise significant concerns regarding public safety, especially given the known history of complaints and recalls associated with Hyundai Theta II engine defects. I am deeply concerned that this vehicle may reflect a broader pattern of defective manufacturing, insufficient quality control. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ODI 11742419

Supplemental Information to Existing NHTSA Complaint involving a 2017 Hyundai Sonata Plug-in Hybrid (VIN: [XXX] ) While traveling at approximately 70 MPH on a heavily traveled highway, the vehicle suddenly and completely lost propulsion without warning. The vehicle rapidly decelerated in traffic, creating a significant safety hazard for my family and surrounding motorists and requiring emergency maneuvering to reach the shoulder. The vehicle was towed to an authorized Hyundai dealership, where diagnostic testing identified multiple high-voltage battery system fault codes: • P0B68 • P0B6D • P0B72 The dealership diagnosed a high-voltage battery system failure requiring battery replacement. The vehicle is currently non-drivable. During my research, I found multiple owner reports involving Hyundai Sonata Hybrid and Plug-in Hybrid vehicles experiencing loss of power, hybrid system failures, limp mode conditions, and propulsion-related incidents. I also learned that Hyundai previously issued Recall 18V166000 involving 2016–2018 Sonata Plug-in Hybrid vehicles due to battery management system and voltage protection device concerns that could result in loss of power while driving. Dealer says does appply for my car. Although my vehicle’s fault codes may differ from those addressed in the recall, both involve battery-related failures capable of affecting propulsion and creating a highway safety risk. My concern extends beyond my individual vehicle. A high-voltage battery or battery management system failure that can cause a complete loss of propulsion at highway speed without warning presents a potentially serious safety risk. I respectfully request that NHTSA evaluate whether similar incidents involving Hyundai Sonata Hybrid and Plug-in Hybrid vehicles indicate a broader safety concern warranting further review. I can provide dealership diagnostic reports, repair estimates, towing records, photos, and videos upon request. Thank you for your consideration, [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ODI 11741174

I am writing to report a serious, premature failure of a primary emissions and safety-related component (the catalytic converter) that has occurred as a direct consequence of a known, unaddressed manufacturing defect in Hyundai's Theta II engine. My vehicle has a documented history of excessive engine oil consumption. This inherent manufacturing flaw causes the engine to burn motor oil at an extreme rate, forcing unburned oil directly into the exhaust system. Over time, this oil has fouled and destroyed the catalytic converter substrate, triggering trouble code P0420 and causing a complete component failure. A dealership inspection at Heritage Hyundai Towson (RO #XXX) confirmed "excessive wear" and failure of the catalytic converter. Because the catalytic converter is failing prematurely due to a liquid defect (excessive oil burning) rather than standard wear and tear, it poses an environmental hazard, compromises vehicle emissions control, and can lead to sudden engine stalling or reduced power while driving, presenting an active safety risk. Hyundai Motor America (Case #XXX) has formally denied assistance to rectify this consequential damage, despite full awareness of the underlying engine defect. I request that NHTSA investigate how Hyundai’s ongoing oil consumption manufacturing issues are causing cascading safety and emissions component failures in these vehicles. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ODI 11740602

The rod bearings failed in the engine. The vehicle is currently at the dealership and is available for inspection. Rod bearing failure can cause complete engine seizure while driving, creating a serious risk of losing vehicle control at any speed. This is a known issue with Hyundai's Theta II engine. Yes. The dealership performed a diagnostic on April 27, 2025 and confirmed rod bearing failure. Yes. The dealership inspected the vehicle and Hyundai corporate opened a warranty case and arranged the repair appointment, initially confirming coverage before later denying the claim without providing documentation. The dealership has also repeatedly failed to provide documentation supporting the denial of my warranty claim despite my requests beginning April 29, 2025. I have also been unable to get callbacks from the dealership after being promised updates on May 1st, May 7th, and after requesting a manager on May 18th. As of May 27, 2025 I have still not received any documentation or a callback. The check engine light came on prior to the failure. I proactively checked and changed the oil, added Lucas oil treatment, replaced the spark plugs, and replaced the battery attempting to diagnose and resolve the issue before bringing it to the dealership. No oil pressure warning light ever appeared. The check engine light persisted despite these efforts which is what led me to bring the vehicle in.

NHTSA ODI 11740495

I have a Hyundai Sonata 2017 one year after I bought the car I started having acceleration problems. I have had the throttle changed and the valve gasket cover repaired. On April 15, 2026 the check engine light came on. On April 29th I got theta 2 emissions update installed at Hyundai Auburn, Al. I took it too auto zone the same day the code P1326 was showing up and P0014. On May 5th my car entered limp mode for excessive oil leakage, I got an oil change April 6, 2026. My car has never done that until the update was installed. I get my oil changed every 6 months and also have sent them records. They denied my claim due to lack of maintenance.

NHTSA ODI 11738867

Engine failed while driving, Took it to dealership and the engine is seized. We were declined by Hyundai an engine replacement even though the Theta 2 engines have a lifetime replacement warranty because these engines are known to fail. They constantly deny due to 'severe owner neglect' because people do their own oil changes.

NHTSA ODI 11737847

The vehicle experienced repeated engine-related failures associated with the P1326 error code, which indicates a potential engine defect. The issue first occurred around February 2023 at approximately 51,500 miles, when a warning light appeared. The problem has recurred multiple times despite inspections and service attempts. In January 2024, a dealership performed a software update related to the P1326 code. Shortly after this update, the engine began consuming excessive oil (approximately 2 liters per 1,000 miles). The condition worsened over time, and the vehicle failed an oil consumption test conducted by a dealership. The issue was confirmed by an authorized dealership, which ultimately diagnosed the engine as failed and requiring replacement in May 2026 at approximately 99,000 miles. The problem has been reproducible, with the P1326 warning code appearing multiple times over the life of the vehicle. This condition creates a significant safety risk because the engine may lose power, misfire, or stall unexpectedly while driving, increasing the risk of a crash, especially at highway speeds or in traffic. The vehicle has already experienced engine misfire and severe performance issues. Warning indicators included the P1326 error code and check engine light, which first appeared in 2023 and recurred multiple times thereafter. The engine oil consumption issue developed after the 2024 service and continued to worsen. The failed engine is currently available for inspection upon request.

NHTSA ODI 11737552

Engine experienced severe metallic knocking and loss of power. A certified Hyundai technician confirmed a FAILED Bearing Clearance Test (RO #354331). Hyundai Motor America is refusing to honor the Engine II Class Action Settlement warranty, citing internal code A99 because the vehicle was purchased at an auction, even though the title is CLEAN. This pose a safety risk of engine seizure and potential fire.

NHTSA ODI 11736427

Consistent burning of oil

NHTSA ODI 11735288

The failed component is the engine assembly in my 2017 Hyundai Sonata SE with the 2.4L Theta II GDI engine. The failure involves excessive oil consumption and internal engine failure, specifically suspected piston ring deterioration allowing oil to pass into the combustion chambers. The vehicle is available for inspection upon request. Safety was put at risk because the engine was losing oil rapidly. If the oil level drops too low, the engine can seize, stall, or lose power while driving. Sudden engine failure at road or highway speeds could increase the risk of a crash. The issue required constant oil monitoring and made the vehicle unsafe to rely on. The problem was confirmed by both an independent repair shop and a Hyundai dealership. At about 99,813 miles, an independent shop diagnosed oil burning from the tailpipe. I then paid for major repairs, including cylinder head and valve work, but the oil consumption continued. A later independent inspection found internal oil consumption consistent with failed piston rings and oil bypassing into the combustion chambers. The Hyundai dealership performed Hyundai’s oil consumption testing process, including combustion chamber cleaning and rechecking oil level. The vehicle failed and engine replacement was approved. The dealer quoted $11,400-$12,000 for replacement. The vehicle has been inspected by an independent repair facility, a Hyundai dealership, and reviewed by Hyundai Motor America Customer Care under case number 42489659. Hyundai denied assistance, stating the vehicle is outside warranty due to time and mileage. Symptoms first appeared around 99,813 miles and included excessive oil consumption, burning oil from the tailpipe, reduced power/dragging, abnormal rattle/noise during low-speed acceleration, and poor fuel economy. After repairs, the oil level still dropped below minimum quickly. I am filing this complaint because this condition may cause sudden engine damage, stalling, or loss of power while driving.

NHTSA ODI 11735000

See attached document for complaint.

NHTSA ODI 11733236

Burns through oil Oil will be black and barely any on the dip stick Cannot make it to recommended oil change miles or date Goes into limp mode

NHTSA ODI 11732386

I am submitting a vehicle safety complaint regarding a recurring HEV warning system indicator affecting my 2017 Hyundai Sonata Hybrid that was not properly diagnosed despite multiple service visits to Nalley Hyundai beginning around July or August 2022. During several service visits while the vehicle remained covered under an extended warranty, I reported the HEV warning indicator to the dealership. Each time the vehicle was returned to me, the warning light was no longer illuminated, giving the appearance that the issue had been resolved. I was not billed for these visits. However, I was informed that the dealership could not determine the cause of the warning indicator, and no permanent repair solution was completed. Because this issue involves the hybrid electric system, I am concerned this may represent a safety-related condition affecting vehicle reliability and drivability. The warning indicator has continued intermittently and has now progressed to the point that my vehicle is no longer dependable transportation. I respectfully request that this complaint be reviewed as a potential hybrid system warning indicator concern affecting the 2017 Hyundai Sonata Hybrid.

NHTSA ODI 11729105

The contact owns a 2017 Hyundai Sonata. The contact stated that the front driver’s side seat belt failed to lock securely. The contact stated that the seat belt loosened unexpectedly and failed to properly protect the driver while operating the vehicle. The dealer was notified of the failure. The vehicle was not repaired. The manufacturer was notified of the failure. The failure mileage was 102,000.

NHTSA ODI 11727305

Care recently became inoperable. The engine was knocking, then stalling and then inoperable. Checked Hyundai website to find Engine Recall describing exactly what my Hyundai was/is experiencing. I brought vehicle to Clay Cooley dealership (39444 Lyndon B Johnson Fwy, 75232) and explained that I see the recall on the Hyundai website describing what my vehicle is experiencing. After their service mechanics review, the Service Department Representative falsely accusing me of the engine failure, stating that I "must not have changed my oil regularly". According to the service department, my 2017 Hyundai Sonata (132,000 miles) is not covered in the engine recall, and I must pay $4,926.53 for the repair. cc: FTC - ReportFraud.ftc.gov Texas Attorney General - Consumer-Protection/file-consumer-complaint

NHTSA ODI 11725990

The contact owns a 2017 Hyundai Sonata. The contact stated that while his wife was driving at an undisclosed speed, the vehicle experienced engine failure. The vehicle made a knocking sound prior to the failure. No warning lights were illuminated. The vehicle was towed to the residence and eventually towed to the dealer, but was not diagnosed or repaired. The dealer acknowledged the engine failure and that the failure was a common failure. The dealer declined the repair due to a lack of service records. The contact was offered a combustion cleaning; however, the vehicle was disabled. The manufacturer was notified of the failure. The approximate failure mileage was 95,000.

NHTSA ODI 11724054

The contact owns a 2017 Hyundai Sonata. The contact stated that the vehicle had experienced excessive oil consumption, caused by engine rod bearing failure. The engine rod bearing failure caused excessive oil consumption and premature spark plug fouling, requiring the frequent replacement of the spark plugs. The dealer was notified of the failure. The vehicle was not repaired. The manufacturer was notified of the failure. The failure mileage was approximately 132,000.

NHTSA ODI 11722532

Sun roof flew off while driving, the metal framing was twisted and dent. Sun Roof was closed at the time. Pictures were sent to insurance company but no one has looked at it yet. No warning. Sun roof was working properly.

NHTSA ODI 11720516

I have a 2017 hyundai sonata sport,it started using a lot of oil,one day I was driving and it just lost speed and the car just started jerking. I checked the spark plugs and oil had gotten on them. I changed the spark plugs,drove it for about 2 weeks and it did it again. I was constantly having to put oil it and changing the spark plugs every 2 weeks. The check engine light would come on every time this happened. I took it to a hyundai dealership they first wanted to do a oil test which they realized would not work because it was using to much oil ,second they wanted to do some other test that would cost almost $300 dollars which would still not determine if I would be eligible for the recall. Can i get some help please,please

NHTSA ODI 11719775

Here is your updated review with that included: ⸻ I am very disappointed with Hyundai Motor America and the service I received at Hyundai of Renton. I own a 2017 Hyundai Sonata and received a letter about a required software update and ignition cylinder protector due to known theft issues. I went to the Renton dealer for the recall service. They performed the software update and were supposed to install the ignition cylinder protector. Unfortunately, my car was later stolen because of this exact issue. The ignition was damaged during the theft, and I had to replace it myself just so I could drive the car. When I returned to the dealer, they refused to install the ignition cylinder protector, saying the ignition was broken. It was broken because of the theft — which happened due to Hyundai’s known defect. After the recall software update, my key fob also stopped working properly. I went back to the dealership, and they refused to fix or properly reprogram my key fob. On top of that, the service manager, John, was very rude and unprofessional. This has been the worst experience I’ve had with a vehicle and a dealership. Because of this situation. Very disappointed.

NHTSA ODI 11719428