Symptoms

The Symptoms section helps you identify early and advanced warning signs of a failing catalytic converter before the problem turns into an expensive repair. Many drivers ignore these signs because the car may still run—but doing so can damage the engine, reduce fuel efficiency, and cause emissions test failure.

If you’re seeing a check engine light, noticing a strange smell, hearing rattling noises, or experiencing loss of power, the articles in this category explain what those symptoms mean and what to check next.