Check Engine Light Flashing

A steady check engine light means the engine's computer has detected something worth checking, but it isn't happening at a rate that requires immediate action. A flashing light means an active misfire is occurring right now, sending unburned fuel into the exhaust where it can overheat and damage the catalytic converter. The distinction matters — steady means schedule a visit, flashing means reduce your speed and get it looked at right away.

You can drive gently to the nearest safe stopping point, but continuing to drive normally with a flashing light risks expensive damage to the catalytic converter from an active misfire. If you're on the road when it starts, ease off the accelerator, avoid highway speeds if possible, and get to a shop as soon as you can rather than finishing out a long drive.

Sometimes a flashing light will settle into a steady light once the misfire event passes, but that doesn't mean the underlying cause is resolved — the code and the risk are both still there. Treat a light that was recently flashing with the same urgency as one that's actively flashing, since whatever caused it hasn't actually been fixed just because the light changed.

A misfire severe enough to flash the light doesn't always feel dramatic from the driver's seat — you might notice a little roughness or nothing obvious at all. The exhaust and catalytic converter don't get that same benefit of the doubt, since they're absorbing the unburned fuel regardless of how the car feels to drive. It's worth having it checked even if driving feels normal.