An engine misfire may feel like a rough idle or hesitation, but continuing to drive can quickly lead to serious catalytic converter damage. A flashing check engine light often means unburned fuel is entering the exhaust system—something the converter is not designed to handle continuously.
A misfire happens when a cylinder fails to properly ignite the air-fuel mixture. Worn spark plugs, failing ignition coils, fuel injector problems, vacuum leaks, or internal engine issues are common causes. When combustion doesn’t occur, raw fuel moves into the catalytic converter.
The catalytic converter is built to burn small amounts of leftover hydrocarbons. Excess fuel, however, causes extreme heat. That heat can melt or damage the internal ceramic substrate, leading to restriction and permanent failure.
Catalytic converter replacement is far more expensive than most misfire repairs. Spark plugs or coils are minor by comparison, while converter replacement can cost thousands depending on the vehicle. A restricted converter can also cause power loss, overheating, and additional engine stress.
Misfiring engine symptoms include shaking, hesitation, reduced power, poor fuel economy, and a flashing check engine light. A flashing light signals active damage risk.
If your engine runs rough or the check engine light is flashing, schedule an inspection immediately. Addressing a misfire early is almost always far less expensive than replacing a damaged catalytic converter.