If the above methods don't work, it may be necessary to replace the catalytic converter. This is a more involved process that requires:

Pour a bottle into a quarter tank of gas, drive normally. Review: These are solvents (e.g., Cataclean, CRC). They can dissolve some varnish and carbon, but they cannot fix a melted core or oil-fouled cat. Works best as preventative maintenance. User reports are mixed—many see no change.

The catalytic converter is an emissions control device that reduces pollutants in a vehicle's exhaust system. Over time, it can become clogged with debris, carbon deposits, and other contaminants, leading to decreased performance, fuel efficiency, and potentially causing the vehicle to fail emissions tests.

That being said, here's a step-by-step guide on how to unclog a catalytic converter:

Rarely. Once the ceramic honeycomb inside is melted, cracked, or coated with oily ash, cleaning is a temporary fix at best. For a permanent solution, replacement is the only reliable method. However, if the clog is light (carbon buildup), some methods buy you time.