2017 Hyundai Sonata: engine stalls while driving

Filed Sep 4, 2026 · Engine · UT

The vehicle suffered a sudden, catastrophic internal mechanical engine failure out of nowhere without any warning lights or previous symptoms. An inspection of the engine cylinder revealed a physical hole blown through the top of the Cylinder 2 piston, causing immediate and complete loss of engine compression. This sudden structural failure caused the vehicle to completely lose all propulsion and stall unexpectedly while in operation, creating an immediate, severe safety hazard on the road.This vehicle features Hyundai's 2.4L Theta II Gasoline Direct Injection (GDI) engine, a family with a well-documented history of manufacturing defects, severe oil consumption, and catastrophic internal structural failures. Because this failure occurred instantly and without a progressive warning, it put occupants at risk of a severe rear-end collision or stranding in an unsafe traffic pattern. I am filing this safety report because the catastrophic destruction of the internal engine components presents a persistent and dangerous hazard to public safety.

Filed Jun 6, 2026 · Engine, Suspension · PA

[XXX] [XXX] [XXX]; [XXX] [XXX] [XXX] Date: XXX To: the federal safety agency 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)

Filed May 28, 2026 · Engine · MD

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 the federal safety agency 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)

Filed May 13, 2026 · Engine · SC

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.

Filed Apr 30, 2026 · Engine · TX

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.

Filed Mar 21, 2026 · Engine · TX

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

Filed Jan 24, 2026 · Engine · AZ

My 2017 Hyundai Sonata is exhibiting a severe metallic knocking noise and metal debris in the engine oil—primary indicators of the Theta II engine defect (the federal safety agency Campaign 17V578). These symptoms indicate imminent engine failure, posing a significant stall and crash risk. On or around 8/20/25, I took the vehicle to Earnhardt Hyundai-San Tan. I informed the technician of the oil burning and metal shavings. They refused to perform the recall repair and charged a $200 diagnostic fee for an inspection related to a federally mandated safety recall. Under federal law (49 U.S.C. Chapter 301), recall remedies must be provided at no cost to the owner. Furthermore, components were not reassembled correctly during the inspection. The vehicle is now leaking oil onto my driveway and has been rendered inoperable. It has not been driven since I picked it up on August 25, 2025. I am requesting that Hyundai be compelled to perform the recall remedy and reimburse the unauthorized diagnostic fee.

Filed Jan 19, 2026 · Engine, Transmission · VA

My vehicle has a documented excessive oil‑consumption defect. After a 1,000‑mile oil‑consumption test performed by a Hyundai dealership, the engine was found to have consumed 2.8 quarts of oil, which is far above normal and poses a safety risk. The dealer referenced TSB 23‑EM‑008H and recommended a chamber cleaning but could not guarantee it would resolve the issue. Hyundai Motor America declined to cover the repair and refused to escalate my case. This level of oil consumption is consistent with known Theta II engine defects that have led to engine seizure, stalling, and fire in other vehicles. I am reporting this as a safety concern due to the risk of sudden engine failure while driving.

Filed Jan 19, 2026 · Engine · FL

The 2017 Hyundai Sonata has had an ongoing engine malfunction defect that is causing engine knocking, stalling, and smell and rapid depletion of oil. The continuous issues are concerning especially when the car is not driven on a regular basis as it is utilized as a second vehicle. This has been a noticeable issue for quite sometime now. I have taken the car to the Hyundai dealership on multiple occassions after notably heavy oil consumption in a short time period in between scheduled oil changes. I am told by the dealership that it is evident that the engine is rapidly processing and burning oil inappropriately from a possible manufacturing defect recall related to connecting-rod bearing failure that was issued by Hyundai for various Hyundai models. The damaged engine may stall, increasing the risk of a crash. In addition, oil may leak onto hot exhaust components, increasing the risk of fire.

Filed Nov 29, 2025 · Electrical, Engine · TX

e vehicle is burning approximately 2 quarts of oil every month with no external leaks. This indicates severe internal oil consumption, which is a known defect in Hyundai’s Theta II 2.4 GDI engines. I discovered oil inside the VVT solenoid electrical connector and on other wiring, which shows oil is traveling through the engine harness. This causes hesitation, rough running, and the risk of sudden engine power loss. The vehicle feels unsafe to drive because the oil level drops quickly, and the engine could seize or stall while driving. Hyundai vehicles of this generation have a history of excessive oil consumption, piston ring failures, and engine fires, and I believe my vehicle is experiencing the same defect. This is a serious safety concern.

Filed Sep 11, 2025 · Engine, Transmission · NV

What component or system failed or malfunctioned, and is it available for inspection upon request? The engine in my 2017 Hyundai Sonata Sport is defective. Oil pressure failed testing, oil contamination was found on the oil pressure sensor and connector, and the vehicle has experienced excessive oil issues. The engine is still in my possession and available for inspection upon request. How was your safety or the safety of others put at risk? The vehicle has gone into limp mode on the highway, which caused a sudden loss of power and created a dangerous situation in traffic. The car also shakes, misfires, and loses power unexpectedly, which could lead to stalling or loss of control at highway speeds. I do not feel safe driving the car. Has the problem been reproduced or confirmed by a dealer or independent service center? Yes. Multiple Hyundai dealerships have inspected the car. One confirmed low oil pressure and oil contamination at the sensor. Previous visits dismissed the oil warning and charged me for oil replacement instead of identifying the underlying defect. Has the vehicle or component been inspected by the manufacturer, police, insurance representatives or others? Yes. The vehicle has been inspected by Hyundai dealers multiple times. I also have two inspection reports from the same dealer just two weeks apart with contradictory findings the first showing no oil issue, the second confirming oil contamination and failed oil pressure. Were there any warning lamps, messages or other symptoms of the problem prior to the failure, and when did they first appear? Yes. The oil warning light and check engine light have both come on. The vehicle has gone into limp mode, and symptoms have included shaking, misfiring, rough idling, and loss of power. These issues began months ago and have continued despite repeated service visits.

Filed Aug 22, 2025 · Engine · IL

What component or system failed or malfunctioned, and is it available for inspection upon request?\n' + 'The engine in my 2017 Hyundai Sonata is defective. It burns oil excessively, fouls spark plugs and ignition coils, and causes continuous misfires. The engine is still in my possession and available for inspection.\n' + 'How was your safety or the safety of others put at risk?\n' + 'The engine misfires cause my car to shake violently while driving, lose power unexpectedly, and turn on the check engine light. This creates a risk of stalling or losing control while driving at highway speeds, endangering myself and others. I no longer feel safe driving the car.\n' + '\n' + 'Has the problem been reproduced or confirmed by a dealer or independent service center?\n' + 'Yes. Multiple independent mechanics have confirmed that the misfires and repeated spark plug/coil failures are caused by the engine itself, not just normal wear. Hyundai dealers acknowledged the excessive oil consumption and advised combustion cleanings, which did not resolve the issue.\n' + '\n' + 'Has the vehicle or component been inspected by the manufacturer, police, insurance representatives or others?\n' + 'Yes. The vehicle has been inspected by multiple Hyundai dealerships (including McGrath Hyundai) and independent service centers (Pep Boys, AAMCO, and others). All noted ongoing oil-related issues and repeated failures tied to the engine.\n' + '\n' + 'Were there any warning lamps, messages or other symptoms of the problem prior to the failure, and when did they first appear?\n' + 'Yes. The check engine light has come on repeatedly over the last two years. Symptoms include rough idling, heavy shaking, loss of power, and repeated ignition coil and spark plug failures (monthly or more often). The problem began within the first year of ownership and has persisted ever since despite repairs.