NHTSA Complaint #11664986 — 2018 HYUNDAI SONATA

Multiple critical mechanical and safety issues have occurred with my 2018 Hyundai Sonata Sport. The vehicle has experienced persistent engine misfire, a severe oil leak, emissions system failure, and extensive paint deterioration. A certified technician confirmed an active oil pan leak with no dashboard warning lights, posing a fire and stalling hazard. To prevent further damage, I replaced the entire oil pan and spark plugs at a personal cost of approximately $800 at Firestone Complete Auto Care. The check engine light revealed diagnostic code P0420 – Catalyst System Efficiency Below Threshold (Bank 1). An O’Reilly emissions scan confirmed the catalytic converter failure, and emissions status was marked “RED.” The vehicle will not pass an OBD-based emissions test. At 149,219 miles, Hyundai refused warranty coverage due to mileage. A certified Hyundai dealership quoted $3,722 to replace both the catalytic converter and valve cover gasket, which remains unaffordable and unrepaired. In addition, the factory-applied white paint began peeling severely from the hood and roof. Although Hyundai issued a warranty extension for this known defect, the dealership refused to repaint the hood, citing a minor dent — even though the peeling is clearly unrelated. The exposed metal has started to rust, risking structural deterioration. All concerns have been evaluated by certified Hyundai service and independent professionals. These combined mechanical, emissions, and exterior failures raise serious safety and durability concerns. I am filing this report to document manufacturer-related defects that may affect other owners of this model and year.