The exact problem causing the flashing light varies, but it often suggests a problem that could damage the catalytic converter, such as:
* Misfire: One or more cylinders aren't firing properly. This is a common cause.
* Severe lack of oil: This can quickly lead to catastrophic engine failure.
* Other major issues: While misfires are common, other severe problems can also trigger a flashing light.
You should pull over safely as soon as possible, and avoid driving further than necessary. It's best to have your vehicle towed to a mechanic for diagnosis and repair. Ignoring the issue could lead to significant engine damage and a much more expensive repair bill in the long run.