Replacement Parts Guidelines - Aftermarket, Performance
and Add-On Parts Regulations

This page last reviewed October 7, 2008

The following list will help you determine if a part for your vehicle is a replacement part and legal for use on pollution. Check the manufacturer's catalogue to verify vehicle application and look for disclaimers, such as "Not legal for street use in California."
Air Cleaner
Most emission controlled vehicles will have an air cleaner that is a closed element type or thermostatically controlled. A replacement air cleaner must meet the same specifications as the original and connect to any emissions equipment that was attached to the original equipment air cleaner. Any replacement air cleaner elements may be used as long as they meet original factory specifications. Any air cleaner that does not meet the original factory specifications requires an Executive Order to be legal for street use.
Cams
The manufacturer of replacement cams determines which of their parts are considered replacements for original equipment. These replacement cams are then listed by vehicle year, make, model and engine size in the manufacturer's catalogue. A replacement cam must have exactly the same specifications (grind) as the original part. Cams that have different specifications than the original part require an Executive Order to be legal for street use.
Carburetors
The manufacturer of replacement carburetors determines which of their models are considered replacements for original equipment. These replacement carburetors are then listed by vehicle year, make, model and engine size in the manufacturer's catalogue. Carburetors not listed as replacement parts by their manufacturer must have an Executive Order to be legal for street use.
Catalytic Converters
A legal aftermarket catalyst is one that is listed in an ARB approved manufacturers catalogue for the year, make, model, and engine size of vehicle on which it is being installed. Manufacturers of aftermarket catalytic converters must obtain an Executive Order for their products from the Air Resources Board in order to be listed in an approved catalogue.
Coils and Ignition Wires
Any type of coil or ignition wires may be used as long as they meet original manufacturer specifications.
Computer Chips
Replacement computer chips must be an original equipment manufacturer part. Aftermarket computer chips must have an Executive Order to be legal for street use.
Electronic Ignitions
The manufacturer of replacement electronic ignitions determines which of their models are considered replacements for original equipment. These replacement electronic ignitions are then listed by vehicle year, make, model and engine size in the manufacturer's catalogue. Electronic ignitions or electronic point replacement units for vehicles not originally equipped with these items require an Executive Order to be legal for street use. Swapping electronic ignitions from different years, engines, or makes is illegal.
Distributors
The manufacturer of a replacement distributor determines which of their models are considered replacements for original equipment. These replacement distributors are then listed by vehicle year, make, model and engine size in the manufacturer's catalogue. Swapping distributors from different years, engines or makes is illegal. Aftermarket distributors that are not listed as replacements for the original part require an Executive Order number to be legal for street use.
Fuel Injection
The manufacturer of replacement fuel injection systems determines which of their systems are considered replacements for original equipment. These replacement fuel injection systems are then listed by vehicle year, make, model and engine size in the manufacturer's catalogue. Fuel injection systems not listed as replacement parts require an Executive Order to be legal. Modifications that change a vehicle from fuel injection to carburetion or from carburetion to fuel injection also require an Executive Order to be legal.
Fuel Tanks
Replacement fuel tanks must be identical to the original part. Add-on fuel tanks, or tanks with greater capacity than the original tank are legal for street use only if they have been issued an Executive Order.
Heads
Replacement heads must be identical to the original part. Head swaps from different years, engines or makes are illegal. Aftermarket heads or valve train components that are not made to the same specifications as the original parts require an Executive Order to be legal for street use.
Headers

Non-Catalytic Converter Equipped Vehicles

Headers for non-catalyst equipped vehicles are considered legal replacement parts as long the replacement header allows for the installation of all smog control equipment originally attached to the stock exhaust manifold. Depending on the vehicle, some of the equipment that would normally be attached to the exhaust manifold includes:

  • Air Injectors

  • Heat Shields for the Thermostatic Air Cleaner

  • Heat Risers

  • EGR System Hookups

  • Fuel Evaporation Systems

Catalytic Converter Equipped Vehicles

Headers for use on catalytic converter equipped vehicles require an Executive Order to be legal for street use.

Intake Manifolds
The manufacturer of replacement manifolds determines which of their models are considered replacements for original equipment. These replacement manifolds are then listed by vehicle year, make, model and engine size in the manufacturer's catalogue.
Replacement manifolds may be made of a different material than the original part, for example polished aluminium instead of cast iron, but the design of the casting must be the same. Any manifold not listed as replacement part by its manufacturer must have an Executive Order to be legal for street use.
Carburetor adapter plates are not legal unless they are an integral part of a replacement manifold.
Other Internal Engine Parts
Replacement internal engine parts, such as pistons, rods, or the crank, must be designed to factory specifications. Oversize parts can be used as long as they are within factory tolerances for replacement engine parts. Any part not built within factory specifications requires an Executive Order to be legal for street use.
Transmission or Transaxle
Transmissions and transaxles changes alone are not legal. Transmissions and transaxles can only be changed along with their matching engine. The total engine transmission package must conform to the engine change requirements above.
Replacement Engines
Entire engines can be replacement parts. As with any other replacement part, the engine must be identical to the original. If the replacement block or engine is obtained without emissions equipment, all the equipment from the original engine must be installed on the replacement block.
If the engine is not identical to the original then it is not a replacement part, instead it is considered an engine change.
Engine changes are a modification that must meet certain requirements to be legal (please see "Engine Changes").
Japanese Replacement Engines
Used engines imported from Japan can be used as replacement engines as long as the engine being used has been identified as functionally identical to the original engine. Please refer to the engine importers catalogue to determine if a replacement engine is legal for installation in your vehicle.           
Engine Changes
Engine changes are legal as long as the following requirements are met to ensure that the change does not increase pollution from the vehicle:
  • The engine must be the same year or newer than the vehicle.

  • The engine must be from the same type of vehicle (passenger car, light-duty truck, heavy-duty truck, etc.) based on gross vehicle weight.

  • If the vehicle is a California certified vehicle then the engine must also be a California certified engine.

  • All emissions control equipment must remain on the installed engine.

  • Vehicles converted to 100% electric drive, with all power supplied by on-board batteries are considered in compliance with the engine change requirements. All fuel system components must be removed prior to inspection. For additional information contact the ARB helpline at (800) 242-4450

After an engine change, vehicles must first be inspected by a state referee station. The vehicle will be inspected to ensure that all the equipment required is in place, and vehicle will be emissions tested subject to the specifications of the installed engine.
Exemptions for Uncontrolled Vehicles
Vehicles that were manufactured before emission control regulations took effect are called uncontrolled vehicles. Aftermarket parts regulations and anti-tampering laws do not apply to these vehicles.
Uncontrolled vehicles may have any aftermarket add-on or modified part installed as long as the vehicle can still meet the tailpipe emission standards for the year of the vehicle. Uncontrolled vehicles must retain any original or retrofit crankcase control (PCV) devices and NOx device required for the year of the vehicle.
The following vehicles are considered uncontrolled vehicles:
  • 1965 and Older : U.S. Manufactured California Certified Vehicles

  • 1967 and Older: U.S. Manufactured Federally Certified Vehicles

  • 1967 and Older: Foreign Manufactured Vehicles
For More Information
To verify Executive Order numbers, or for questions about the replacement parts guidelines, please contact the California Air Resources Board Vehicle Hotline:

(800) 242-4450 California
(626) 575-6858 Non-USA

To obtain a list of ARB Executive Order parts, or for information on the Executive Order certification process for aftermarket parts manufacturers, please write to:

California Air Resources Board
Aftermarket Parts Section
9480 Telstar Avenue, Suite 4
El Monte, California  91731


preload