NHTSA Complaint #11710036 — 2011 HYUNDAI SONATA

I am reporting a safety-related engine failure involving my 2011 Hyundai Sonata 2.0T. In November 2025, at approximately 90,000 miles, the vehicle experienced a sudden engine failure while driving, including loss of power and abnormal engine noise. This created an unsafe driving condition and required the vehicle to be removed from service. Component/System Involved: The engine (Theta II 2.0T) suffered a catastrophic internal failure. The engine and internal components remain available for inspection upon request. Safety Risk: The sudden loss of engine power reduced my ability to maintain speed and maneuver in traffic, posing a safety risk to myself and other motorists. Confirmation and Inspection: The failure was confirmed by an authorized Hyundai dealership, which inspected the vehicle and documented the internal valve train condition through photographs. Hyundai Motor America reviewed the claim and issued a written denial. No independent third-party technical inspection was performed. Prior Symptoms: Before the failure, the vehicle had a history of excessive oil consumption requiring frequent monitoring and oil addition despite regular maintenance. Abnormal engine noise was present for approximately one minute before failure. No warning lights adequately predicted the sudden failure. Additional Context: This vehicle is equipped with a Theta II engine, which has been the subject of prior recalls and settlements related to internal engine defects. Hyundai denied warranty coverage alleging “exceptional maintenance neglect”; however, inspection photos show a well maintained valve train with no sludge or oil flow obstruction, only light surface varnish consistent with normal engine aging. I am concerned this failure represents a continuation of a known Theta II engine defect (confirmed by Hyundai technician who performed inspection with OBD code P1326 followed by engine failure) and poses a serious safety risk due to sudden loss of engine power while driving.