2015 Hyundai Sonata: engine knocking or ticking

Filed Oct 28, 2026 · Brakes, Electrical · CO

On Wednesday, October 21, 2026, our 2015 Hyundai Sonata with the 2.4L Theta II GDI engine suffered a sudden, complete engine seizure while traveling about 75 mph on I-25 Southbound near Castle Rock, CO. A family member was driving. Warning lights across the car began flashing, the engine made a loud grinding noise, and the brakes stopped working. Over a long distance, the driver was able to get the car onto the shoulder and bring it to a stop, then engage the parking brake. There was no collision and no injuries, 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.

Filed Oct 14, 2026 · Engine, Fuel system · MS

A franchise dealership performed a federally mandated safety recall service (ECM Software Update) and a knock sensor replacement on this 2015 Hyundai Sonata 2.0L Turbo. To perform these specific repairs, the technician had to work directly around the intake and turbocharger assembly workspace. Immediately after picking up the vehicle, it suffered a sudden and dangerous loss of power and refused to accelerate normally on the highway, creating a severe traffic hazard. Upon an immediate emergency inspection by the same service center 5 days later, the dealership documented in writing that the turbocharger intercooler hose clamps were completely off/unfastened. Because the technician left the clamps disconnected, the turbo lost sealed pressure, failed completely, and began dumping high-pressure engine oil backward through the air filter intake box. The service center is now refusing to take responsibility for the mechanical safety failure directly caused by their technician's recall repair negligence.

Filed Oct 13, 2026 · Engine · FL

Hyundai Motor America is explicitly refusing to honor the mandatory safety recall and lifetime warranty extension for a catastrophic rod bearing failure on my 2015 Hyundai Sonata (VIN [XXX]). The engine suffered a sudden internal connecting rod bearing seizure while operating, causing a complete loss of motive power and creating an immediate hazard. Hyundai Corporate Escalations issued a blanket denial solely because the vehicle carries a rebuilt title. However, the vehicle's official Hyundai portal confirms that Service Campaign 953 (the Knock Sensor Detection System software update) was successfully completed on XXX. The engine failure matches the exact factory manufacturing defect (internal oil starvation from manufacturing debris) that is the subject of the In re: Hyundai and Kia Engine Litigation. The external collision history that led to a structural/rebuilt brand has absolutely zero mechanical correlation to a sealed, internal crankshaft block defect. Hyundai is acting in bad faith by using an unrelated title status to evade a federal safety recall mandate and escape liability for a dangerous, stalling powertrain defect. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Aug 8, 2026 · Engine · FL · fire

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)

Filed Aug 5, 2026 · Engine · CA

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.

Filed May 30, 2026 · Engine · GA

2015 Hyundai Sonata 2.4L Theta II GDI engine experienced complete failure due to connecting rod bearing defect. Vehicle was taken to a Hyundai dealership prior to failure to report engine knock symptoms. Dealer confirmed KSDS (Service Campaign 953) was installed but performed no inspection and provided no repair order. Engine subsequently failed with no warning light activation despite KSDS being installed. This is a known defect covered under the Theta II class action settlement lifetime warranty. Warranty repair has not been provided and no loner car has been provided.

Filed May 1, 2026 · Engine · DE

Engine – connecting rod bearing failure. Theta II engine. Hyundai confirmed the defect via Bearing Clearance Test (BCT) on October 3, 2025. The engine can seize without warning, causing sudden loss of power while driving – a clear safety risk. The problem has been confirmed by an authorized Hyundai dealership (Hertrich Hyundai of New Castle). The manufacturer issued Technical Service Bulletin 22‑EM‑001H (TXXI lifetime warranty) covering this exact defect. Despite confirming the failure, the manufacturer has refused to repair the engine. The vehicle is available for inspection upon request. No crash, fire, or injury occurred. Warning signs included engine noise and illumination of check engine light before failure.

Filed Apr 20, 2026 · Engine · OR

since i have owned this car they have replaced the knock sensor twice. there is a recall on the engine for crank bearing wear, my car now is burning through 5 quarts of oil every 2 weeks with no oil leak spots on the ground. i would like them to replace the engine as per the recall. the knock sensor should be an indication of the bearings going bad. i have been getting the run around from the dealer in Salem, Oregon. so, i would like some assistance with this problem thank you for your time.

Filed Apr 4, 2026 · Engine · OH

Engine seized driving down the interstate doing 65 MPH in rush hour traffic could have been rear ended or hit vehicles around me trying to get off the road. Complete loss of power. Power steering was still active brakes were barely working. No warning lights (I had the knock sensor recall performed). Engine simply locked up solid. I was able to safely make it to the disabled vehicle lane and put the car in park. Engine had no sludge buildup and looked excellent once it was disassembled by the dealer. All engine bearings had spun. Engine was completely replaced under the extended warrenty.

Filed Mar 8, 2026 · Engine · SC

Rod bearing failure

Filed Feb 19, 2026 · Engine · GA

Engine has knocking sound. Sudden loss of power and hesitation when accelerating

Filed Feb 17, 2026 · Engine, Fuel system · SC

Component/System Failed: Engine – connecting rod bearing failure consistent with Hyundai Theta II engine defect subject to federal recalls and Consent Orders. The vehicle previously received Recall Campaign 953 (KSDS software update), intended to detect premature rod bearing wear. The engine is currently knocking and has been diagnosed as requiring replacement. The vehicle and engine are available for inspection upon request. Safety Risk: Rod bearing failure can cause sudden engine seizure or stall while driving, creating a significant crash risk due to loss of power steering and braking assist. Engine failure DID occurr despite prior recall software update, indicating potential recall remedy ineffectiveness. Sudden stalling in traffic placed myself and others at risk of collision. Dealer Confirmation: Hyundai of North Charleston confirmed through warranty history a prior engine replacement request (PA) was submitted by a previous owner but denied. The recall repair was never performed. Current diagnostic findings indicate engine failure consistent with known recall defect. However, Hyundai has refused to perform further inspection or goodwill repair solely due to the vehicle’s salvage branding. Inspection History: The vehicle has been inspected by a Hyundai dealership. No engine replacement was completed. Hyundai Customer Care has updated case notes but is declining remedy based on title status rather than mechanical condition. Warning Lamps/Symptoms: The vehicle previously received KSDS software update. Engine knocking developed consistent with rod bearing wear. The software did not provide effective prevention of engine failure. The engine now requires replacement. Hyundai is refusing recall-related remedy due to salvage title (predates my wonder ship by many years), despite federal recall obligations applying to the vehicle VIN. This complaint concerns potential failure of recall remedy effectiveness and denial of defect-related inspection.