Some Hyundai Sonata owners report experiencing a loss of power accompanied by a knocking noise and potential engine failure. These issues may indicate engine misfires, which can manifest as a jerking sensation or knocking sound, and are often signaled by the illumination of the "check engine" light on the dashboard. Additionally, some owners have reported complete engine shutdown while driving, particularly in models from 2011 to 2016, which may be linked to manufacturing defects or poor maintenance. The knocking noise itself could stem from low oil levels, ignition issues, timing problems, or faulty components like rod bearings and knock sensors. To mitigate these problems, some owners have found that using higher octane fuel can help if they were previously using low-octane fuel. Proper maintenance is essential, as engine failures have been reported just outside of warranty periods, especially between 60,000 and 120,000 miles, despite a well-maintained engine typically lasting at least 200,000 miles. In severe cases, a loud knocking noise along with an oil pressure warning light may indicate worn connecting rod bearings, which could lead to oil leaks and even fires. It is advisable for owners experiencing these symptoms to consult a qualified mechanic promptly to diagnose and address the underlying issues to prevent further damage or safety hazards.