Why is my check engine light flashing?
Answered by Super Tire & Muffler · Updated June 19, 2026
Short answer
A flashing check engine light almost always means your engine is misfiring: raw, unburned fuel is reaching the exhaust. That is serious because it rapidly overheats and can destroy the catalytic converter. Ease off the gas, drive gently, and get it diagnosed right away. Unlike a steady light, a flashing one should not wait.
Common causes of a misfire
Misfires often trace back to worn spark plugs, a failing ignition coil, a bad fuel injector, or a vacuum leak. The engine may feel rough, shake at idle, or lose power.
Because the damage to the catalytic converter happens quickly, the smart move is to stop hard acceleration and bring it in rather than finishing a long trip.