eBay allows the sale of catalytic converters except for those that are prohibited by the U.S. government. We don't allow items that are designed to defeat, bypass, or shut down catalytic converters, oxygen sensors, and malfunction indicator lights.
Test pipes are allowed if they are marketed as race car accessories and are listed in the Auto Racing Parts category. Test pipes are not approved for use on street-legal vehicles.
Make sure your listing follows these guidelines. If it doesn't, it may be removed, and you may be subject to a range of other actions, including limits of your buying and selling privileges and suspension of your account.
What are the guidelines?
New catalytic converters that meet the EPA (Environmental Protection Agency) requirements for aftermarket sale
Used catalytic converters that have been recertified
Used catalytic converters that haven't been recertified; the listing can't contain make and model information, and the item must be listed as scrap metal
Oxygen sensor simulators
Malfunction indicator light eliminators
Anything that indicates it will defeat, bypass, or shut down emission control devices
Exhaust pipes and down pipes that are listed in the Auto Racing Parts category
Exhaust pipes and down pipes that are not listed in the Auto Racing Parts category
Exhaust pipes and down pipes that indicate they are street-legal
Exhaust pipes and down pipes that indicate they will bypass or not conform to EPA standards and are not listed in the Auto Racing Parts category