Aftermarket, Performance, and Add-On Parts Regulations

This page last reviewed June 27, 2016

Aftermarket Parts Database of Executive Orders

Exempted parts are add-on or modified parts that have undergone an ARB engineering evaluation. If the part or modification is shown to not increase vehicle emissions, it is granted an exemption to emission control system anti-tampering laws. This exemption is called an Executive Order (EO) and allows the modification to be installed on specific emission controlled vehicles. Every Executive Order part or modification has an assigned number that can be verified by Smog Check stations, BAR Referee stations, or by the ARB.

Other related databases/lists:

*Alert: Please view Executive Orders that were rescinded or withdrawn and the catalytic converters that cannot be advertised, offered for sale, sold or installed.
*Toyota: Please follow this link to see catalytic converters that are legal on 2001-2004 4.7 liter Toyota Sequoia and 2003-2004 4.7 liter Toyota Tundra.

  • 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.

  • Products in Progress List  -  This list expired on December 31, 2011, and is no longer available for viewing.  Add-on and modified parts without an Executive Order after this date will cause the vehicle to fail the visual portion of the Smog Check inspection. Diesel vehicle owners may view additional information regarding these parts.

For more information about add-on and modified parts, or aftermarket catalytic converters, please contact ARB's Public Information Helpline at (800) 242-4450 or via email.

SEARCH FOR EXECUTIVE ORDER (except for catalytic converters):

Executive Order Number: - -
(Optional - Narrows selection on "Select Executive Order" drop down list below)
Select Executive Order:

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LIST EXECUTIVE ORDERS BY DEVICE (except for catalytic converters):

Sort by: Executive Order
Select Device Type:


  • Air Cleaner Modification - modifications to the air cleaner and/or its housing.
  • Air Filter/Intake Modification - open element air filters, modifications to the air flow intake tract, heat risers/preheat ducts.
  • Engine Modification/Engine Change - kits that include multiple engine modifications such as new cylinder heads and camshafts, or boring and stroking; engine changes using an engine certified for another late model vehicle application, with additional engine modifications .
  • Exhaust System/Exhaust Modification - exhaust manifold, exhaust headers, exhaust pipes, crossover pipes, etc.
  • Fuel Line Modification - devices designed to attach to or be inserted in the fuel line.
    Exemptions are no longer required for magnetic devices that are attached to the exterior of the fuel line; these devices have been determined to have no effect on emissions.
  • Fuel System Modification - fuel filters, gas caps, pressure regulators.
  • Intake/Exhaust System - a kit that includes both intake and exhaust components.