Question 1

Is it OK to keep driving with the check engine light flashing?

Accepted Answer

No - not normally, and not for long. A flashing check-engine light specifically signals an active misfire severe enough to send raw, unburned fuel into the exhaust, which can overheat and damage the catalytic converter within minutes of continued hard driving. Reduce speed and load, and get to a stop or a shop as soon as reasonably possible.

Question 2

What is the difference between a flashing and a steady check engine light?

Accepted Answer

A steady light means a fault was detected and stored, but nothing needs immediate attention - you can typically finish your drive and schedule a diagnosis. A flashing light means the fault (almost always a misfire) is happening right now and is severe enough to risk damaging the catalytic converter, which is a reduce-speed-and-get-it-looked-at-soon situation, not a whenever-is-convenient one.

Question 3

Can a flashing check engine light really damage my catalytic converter?

Accepted Answer

Yes. When a cylinder misfires, unburned fuel passes into the exhaust instead of being burned in the cylinder. That fuel ignites inside the hot catalytic converter, which can melt the converter's internal substrate. This is exactly why P0300 and the cylinder-specific misfire codes are rated High severity, and why a flashing light so often leads to a P0420 or P0430 catalyst code afterward if the misfire is not fixed promptly.

Question 4

What usually causes a flashing check engine light?

Accepted Answer

Spark plugs and ignition coils are the most common causes of the misfires that trigger a flashing light, followed by vacuum leaks and fuel injector problems. A code reader narrows it down: P0301-P0304 point to one specific cylinder (making the coil, plug, or injector for that cylinder the prime suspect), while P0300 (random/multiple) more often points to something affecting several cylinders at once, like a vacuum leak or worn plugs across the board.

Check Engine Light FLASHING? Stop - Here Is What It Means