Confirm the catalytic converter is the problem
Check for engine codes and fix underlying issues first
Inspect for physical damage, melting, or rattling
Let the exhaust system cool completely
Wear gloves and eye protection
Remove the catalytic converter if needed and allowed
Use a catalytic converter cleaner additive in the fuel tank
Drive the vehicle to help circulate the cleaner
Soak a removed converter in a catalytic converter cleaning solution
Rinse the converter thoroughly with water if the cleaner instructions allow
Allow the converter to dry completely before reinstalling
Reinstall the converter with new gaskets if needed
Clear diagnostic trouble codes after cleaning
Test drive and recheck for symptoms
Replace the catalytic converter if it is clogged, melted, or damaged beyond cleaning