Aftermarket Catalytic Converters

This page last reviewed on May 9, 2019

Aftermarket catalytic converters must be exempted from California's anti-tampering laws in order to be legally sold and installed in the state. If an aftermarket catalytic converter is shown to be durable and meets vehicle emission control requirements, it is granted an exemption Executive Order (EO) that allows it to be installed on specific emission controlled vehicles.

To search for EOs of exempted aftermarket catalytic converters, please go to the following pages:

*Alert: Please view Executive Orders that were rescinded or withdrawn and the catalytic converters that cannot be installed, sold, offered for sale or advertised.

  • Motorcycle Aftermarket Parts Page - This page has a list at the top containing EOs for motorcycle aftermarket catalytic converters and other critical emission control parts for motorcycles.

To determine the correct catalytic converter part number for your vehicle, you will need its make, model, model year, engine size and test group/engine family designation.

Information About Ammended Regulations for Aftermarket Catalytic Converters

CARB amended the regulations and evaluation procedures in September 2017 incorporating LEV Ill standards and test procedures for the approval of new aftermarket catalytic converters sold in California. These amendments are effective beginning January 1, 2019.

The requirements apply to all new aftermarket converters produced for sale or sold in California after January 1, 2009. The requirements also sunset provisions allowing the sale of certified used catalytic converters beginning July 10, 2008. This means that no used converter can be legally advertised for sale, sold, or installed in California after this date.

The links below provide additional information for manufacturers of aftermarket catalytic converters:

  • Worst Case Test Vehicle Selection for non-OBD II Vehicles (PDF - 9K)
  • Mailout #: MSO 12-03: Rapid Aging Test-A and Furnace-based Incremental Aging Procedures

The links below provide additional information for aftermarket catalytic converter retailers, installers, and consumers:

Materials on installation requirements for new aftermarket catalytic converters previously provided to installers/distributors at public meetings:

  • Slide presentation (PDF - 168K)
  • Installation requirements - questions and answers. (PDF - 31K)
  • Installer's checklist for new aftermarket catalytic converters. (PDF - 85K)
  • Installer's checklist for new aftermarket catalytic converters (en Espaņol). (PDF - 78K)
  • Installation requirements (refer to paragraph (h) of the regulations, pg 18). (PDF - 128K)
  • Vehicle Code section 27156. (PDF - 14K)
  • Sample warranty registration card. (PDF - 706K)

Formal Regulatory Documents for October 25, 2007, Hearing.

The documents pertaining to the Board's adoption of new requirements for replacement catalytic converters include, but are not limited to, the public hearing notice, staff report, and regulations.

Aftermarket Parts Related Workshops and Meetings:

For a complete listing of Public Workshops and Meetings, please visit the Aftermarket Parts Public Meetings wepbpage.

Who can I contact for more information?

For more information about aftermarket catalytic converters, please contact ARB's Public Information Helpline at (800) 242-4450.