Hyundai Sonata Engine problems by year

smoke and loud knocking. This has put me and my daughter at risk. I'm asking NHTSA to investigate why an engine with an update that was installed to prevent what happened could fail on the road, produce that much smoke, and spill oil the way it did. I had a driveway to pull into but another driver might not of have nowhere safe to go. If Hyundai knew this type of failure could happen, I want NHTSA to look at whether the update gives drivers enough warning and whether more needs to be done to keep these cars safe on the road.

mechanic, who diagnosed the vehicle with engine failure. The vehicle was taken to the dealer; however, the cause of the engine failure could not be confirmed. The manufacturer was notified of the failure. The failure mileage was 114,719.

will restart. This situation is extremely concerning because it exposes me, my passengers, and other motorists to a significant safety risk. An unexpected shutdown while traveling on a public roadway could result in a serious accident. Given the vehicle's previous engine failure and Hyundai's subsequent engine replacement, I am requesting a thorough investigation into whether the current malfunction is connected to the replacement engine, its associated components, or another underlying defect. Specifically, I am requesting: A comprehensive diagnostic inspection to identify the cause of the unexpected shutdowns and delayed restarts. A review of the vehicle's previous engine replacement and repair history. Verification of all applicable warranties, extended engine coverage, recalls, and service campaigns. Written documentation of the diagnostic findings and the recommended corrective action. Consideration of full warranty coverage or goodwill assistance for repairs associated with the previous engine replacement or any covered defect. Assistance with safe transportation or towing, given the risk of driving the vehicle in its current condition. I have a dealership service visit scheduled for Saturday, November 7, 2026, and I am notifying Hyundai in advance to ensure that this serious safety concern is formally documented. I respectfully request written acknowledgment of this complaint, a case number, and confirmation that the dealership will inve

beginning shortly after I purchased it brand new. Due to this ongoing issue, I make it a point to keep extra engine oil in my trunk so I can monitor and maintain the proper oil level. On [redacted], I stopped by the Joe Holland Hyundai Service Department and spoke with [[redacted]] about the oil warning light continuing to flicker while driving. Unfortunately, no resolution or explanation was provided. However, [[redacted]] did acknowledge that the engine in my vehicle had previously been identified on a problem list due to a machining error that occurred during the engine manufacturing process. This acknowledgment is particularly concerning because it suggests that Hyundai was aware of a potential manufacturing defect involving this engine. Despite the vehicle's ongoing oil consumption and the appearance of the oil warning light, I have yet to receive a satisfactory explanation or resolution from the dealership. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

engine swap, technicians were physically required to drop the front subframe framework and disconnect the lower suspension linkages and steering column components. The dealership is actively trying to deflect safety accountability for an assembly error. They issued a new estimate attempting to charge me over $3,200 to replace the entire front strut and rear shock assembly, claiming it is a 'pre-existing wear-and-tear' issue due to mileage. However, I hold the dealership's official Multi-Point Vehicle Inspection report from when the car was first dropped off for the engine failure three weeks prior. In that mandatory baseline safety report, their own technician thoroughly checked the under-carriage and officially marked my 'Shock Absorbers / Suspension' and 'Steering Gear Box / Linkage and Boots' as PASSED with green checkmarks. This objective paper trail proves the front chassis was tight, silent, and structurally safe before the repair. The safety hazard was introduced solely during the dealership's engine reassembly. The Service Manager explicitly refused to step out of his office to address this safety complaint, and the dealership released a compromised, structurally unsafe vehicle to a consumer. I request a formal federal safety investigation into this branch's safety compliance regarding recall implementation.

only because traffic was light. The car was towed to a repair shop, then transferred to a second shop, which determined the engine had seized and requires full replacement. This vehicle is covered by Hyundai's Theta II GDI engine campaigns for connecting rod bearing failure. On October 26, 2026, Hyundai told us the Knock Sensor Detection System software update (Campaign 953) was never completed on this vehicle and declined coverage. Neither we nor the prior owners, who are family members, recall receiving any notice of this campaign. All previous check engine lights were diagnosed and repaired at independent shops, including an intake manifold replacement in April 2024, and no shop ever identified an open engine campaign. A full engine seizure at highway speed, combined with the loss of braking, creates a serious crash risk for the driver and surrounding traffic.

There was no collision, injury, smoke, or fire. The sudden, unannounced loss of propulsion created a safety concern because the vehicle could no longer move under its own power. Fortunately, the driver was still on the gas station property and was not blocking traffic. An independent repair shop inspected the vehicle and confirmed that the engine was mechanically locked up. The vehicle was subsequently taken to an authorized Hyundai dealership for inspection. The dealership's service adviser reported lower rod-bearing failure. Hyundai later denied engine-replacement coverage, citing neglect and missing maintenance records. That denial is being disputed through BBB arbitration. The vehicle had received an oil and filter change and a mechanical inspection on August 4, 2026, at 74,548 miles - 15 days and 1,622 miles before the failure. The vehicle remains at the Hyundai dealership, and the engine is available for inspection upon request. The exact underlying cause of the reported bearing failure is UNKNOWN.

The vehicle was taken to the dealer, where it was confirmed that no open recall was associated with the VIN. The dealer replaced several sensors; however, the contact was unable to specify which sensors were replaced. The dealer stated that the vehicle needed to be driven until the next oil service, at which point the oil would be changed and the engine sealed. The contact was referred to the NHTSA hotline to file a safety complaint. The manufacturer was notified of the issue, and a case was escalated. The failure mileage was approximately 70,000.

filter were changed about 730 miles before the failure, with two more documented oil changes in the prior 16 months. Connecting-rod-bearing failure in this engine can cause engine seizure or stalling while driving, which creates a crash risk. The vehicle is at the dealer and has not been repaired. I am reporting this so NHTSA has a record of a Theta II failure in a vehicle covered by these campaigns that was denied repair. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

foot was removed from the brake pedal, the mechanical surge caused the vehicle to unexpectedly lurch forward, fighting against and nearly overriding the factory Auto Hold braking safety feature before finally holding. Luckily, no pedestrian was walking in front of my car when this occurred. No check engine light (CEL) or dashboard warning ever illuminated. This safety compromise is directly tied to an ineffective or adjacent remedy involving Service Campaign 9B1 (Opcode 40D219R0) and Safety Recall 286. Under this Opcode, a factory software flash deleted the standard OBD-II trouble code P0451and substituted it with a manufacturer-specific shadow code P14EE00. This software manipulation suppressed universal emission/pressure sensor faults, masking a volatile physical defect within the high pressure fuel delivery and ignition systems. Dealer diagnostics on a running, compromised engine flagged an improper fuel injector pulse and subsequently a failing Cylinder 3 ignition coil. All four injectors were replaced but only one coil, leaving 3 non-updated , factory defective coils in the engine. The vehicle remains an ongoing highway stalling and brake-override hazard due to an incomplete field remedy of a recall-adjacent system. I've filed a Hyundai Complaint with assigned case number 43394228 regarding Safety Recall 286. (Two episodes of the attempted Auto Hold override occurred - first 09/09/2026 and second 09/29/2026.)