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Engine And Engine Cooling
07/09/2025
The contact owns a 2015 Hyundai Sonata. The contact stated that while operating the vehicle, exhaust fumes were noticed inside the cabin, and the check engine light illuminated before the engine stalled. The vehicle was towed to a local dealer. The cause of the failure was not determined. The manufacturer was notified of the failure. The failure mileage was unknown.
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Engine And Engine Cooling
07/02/2026
The contact owns a 2015 Hyundai Sonata. The contact stated that the vehicle was taken to a local dealer who performed an emission software upgrade. Later, while driving, the air conditioner blew hot air, the thermostat increased to high, and an engine overheating warning message was displayed on the instrument panel. The vehicle was taken back to the dealer, who diagnosed that the thermostat had failed and needed to be replaced. The thermostat was replaced, and the failure was remedied. The manufacturer was notified of the failure. The failure mileage was 74,000.
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Engine
07/04/2026
Engine misfiring and low compression
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Engine
12/31/1969
Oil consumption
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Power Train
07/01/2026
VEHICLE: 2015 Hyundai Sonata, 2.4L Theta II GDI engine Mileage at time of incident: [ 93k Date update performed: June 2026 Dealer/location where update was performed: Fitzgerald Hyundai Gaithersburg, MD DESCRIPTION OF PROBLEM: After my vehicle received the ECM software update issued under Hyundai Service Campaign 9C2 (ECU Software Update for Theta II Emissions Improvement, TSB 25-01-087H / 26-01-013H-1), the vehicle began exhibiting noticeable jerking/hesitation during acceleration that was not present before. For this vehicle this happens consistently after a cold start then does not happen again.
