A flickering check engine light with a rough idle often points to a misfire, vacuum leak, or electrical fault.
Check the codes and ignition components first—and don’t ignore a flashing light.
What a flickering light is telling you
On your Fiat 500X, a check engine light that flickers or flashes while the idle is rough should be treated as a possible active misfire, not just a nuisance light. A misfire means unburned fuel is reaching the catalytic converter, which can overheat and damage it quickly. The most common culprits are worn spark plugs, failing ignition coils, a vacuum leak, a dirty throttle body, or a faulty coil connector. On MultiAir and Tigershark engines, PCV and intake leaks can also cause a lumpy idle that feels like a misfire.
