A flickering check engine light with a rough idle usually points to an active misfire or fuel/air fault on your Genesis G80 II.
Get it scanned soon, check ignition and intake leaks first, and avoid hard driving if the light is flashing.
What a flickering check engine light is telling you
On your Genesis G80 II, a check engine light that flickers or flashes while the engine is running is different from a steady light. A steady light says the computer has stored a fault; a flickering or flashing light often means an active misfire is happening right now. That matches your rough idle, and it should be taken seriously because unburned fuel can overheat the catalytic converter. Have the car scanned for current and pending codes, misfire counters, freeze-frame data, and fuel trims before replacing parts.
