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Power Train, engine
03/16/2026
The incident began following a routine maintenance visit on March 16, 2026, and has been a continuous, ongoing safety hazard every single day since. While the vehicle was in for routine brake service and an oil change, the dealership automatically applied an open, manufacturer-mandated ECU S/W Update THETA II (26-01-013H-1) under Service Campaign 9C2 Emissions (Code NP001-SC9C2) without my prior knowledge of its drivability side effects. This software flash directly compromised the vehicle's powertrain logic, creating two notable, daily safety failures. First, within the first 5 minutes of engine startup, and most pronounced on every cold engine startup, the throttle delivery is highly erratic, causing uncommanded low-speed surging. In a specific incident in a parking lot following a cold start, I accelerated to approximately 15 MPH and completely removed my foot from the accelerator pedal to coast. Instead of slowing down, the vehicle unexpectedly lunged and pulled ahead forcefully a...
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Engine
02/14/2025
On October 2024,I brought the car in to RickCase Hyundai for maintenance and to address an oil leaking issue. I texted the service advisor, “Please do not do the oil change till you find out where the oil is leaking”, I’m replacing it frequentlyWhen I picked up the car and inquired about the leaking, the he told me that there was not an issue. January 2025, the car was driving rough again, noticed the oil low and filled it up. February 2025 driving on 595, The car stopped. I had it towed to Rick Case, they told me I needed to replace the piston. I said no this has to do with the oil consumption issue that I brought the car in October that you never addressed. The four new spark plugs that were put in were burnt on the tips. They went through the warranty issue to get the engine repaired and it was denied. I said this is not a warranty issue. This was a mistake on your part because you never address the oil consumption issue in October 2024. As of June 12,2026, the dealership still has...
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Engine
06/04/2026
The contact owns a 2015 Hyundai Sonata. The contact stated that while idling at a stop light the vehicle suddenly stalled. The engine did not restart and the vehicle was pushed to a nearby parking space. During the failure no warning lights or messages had displayed. The cause of the failure was not yet determined. The manufacturer and local dealer were not yet contacted regarding the failure. The failure mileage was 123,000.
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Engine
04/30/2026
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.
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Engine And Engine Cooling
05/06/2026
The contact owns a 2015 Hyundai Sonata. The contact stated while driving at various speeds, the vehicle skipped and failed to exceed 35 MPH. The contact received notification of Hyundai Service Campaign Number: 9C2 (ECU SOFTWARE UPDATE FOR THETA II EMISSIONS IMPROVEMENT), and the vehicle was towed to the dealer, where it was diagnosed and determined that the catalytic converter was clogged and needed to be replaced at the owner's expense. The vehicle was not yet repaired. The contact's son, who was an independent mechanic, determined that the ECU might have sent erroneous signals to the O2 sensors, who then sent excessive fuel into the catalytic converter, causing a catalytic converter clog. The manufacturer was notified of the failure and was informed of the Service Campaign notification, but the manufacturer denied assistance due to the mileage and lack of warranty coverage. The failure mileage was approximately 140,000.
