NHTSA complaint #11740933

Owner complaint summary

While driving, the check engine light began flashing and the vehicle shook severely due to engine misfiring. The vehicle has had a recurring cylinder 3 misfire throughout ownership. Spark plugs and ignition coils were first replaced around 40,000 miles and replaced again in December 2025 for the same recurring issue. A Hyundai dealership inspected the vehicle and found codes P0300 random misfire and P0303 cylinder 3 misfire. The dealership technician documented that the piston rings did not look good and confirmed the catalytic converter was damaged as a result of the misfires. The vehicle has had an engine rattle at idle, oil consumption, and blow-by since early in ownership. The engine defect is progressive and predates the current mileage. The flashing check engine light and severe shaking while driving at highway speeds created an unsafe condition with other vehicles on the road. The problem has been confirmed by a Hyundai dealership. Hyundai Motor America was contacted and denied goodwill warranty assistance. The vehicle is available for inspection upon request.