Vehicle Aftermarket Parts Manufacturers: Prepare for New CARB Exemption Requirements

September 08, 2020

Starting next year, vehicle aftermarket parts manufacturers will have a new process to navigate to qualify for California’s exemption from anti-tampering laws.

The California Air Resources Board (CARB) has adopted, and will put into effect sometime in 2021, updated aftermarket parts approval procedures to obtain an executive order (EO) for aftermarket parts that have the potential to impact emissions. CARB says the new procedures are intended to update, clarify, and streamline its decades-old rules governing the review and issuance of EOs. The new process certainly updates existing regulations and addresses technologies that did not exist at the time the current requirements were promulgated.

Whether this streamlining promoted by CARB will benefit manufacturers remains to be seen. The new process may allow CARB to be more efficient in reviewing applications and approving EOs, but the changes may also increase the burdens on certain manufacturers that will have to submit a larger number of applications to cover their product lines, which may result in additional testing obligations and expense.


California’s anti-tampering law (California Vehicle Code § 27156) generally prohibits the sale, offer for sale, or installation of aftermarket parts that have the potential to impact emissions, unless such parts have been granted an “exemption” from CARB in the form of an EO.[1]

In order to issue an EO for an aftermarket part, CARB must determine that the part does not reduce the effectiveness of any required motor vehicle pollution control device or that resulting emissions are at levels that comply with existing state or federal standards. To meet this standard, aftermarket parts manufacturers submit EO applications that often include vehicle or engine testing results to demonstrate that their parts do not reduce the effectiveness of any emissions control device. CARB receives more than 200 applications for exemptions annually.

The growing number of applications, together with the development of modern emissions control systems and technologically advanced aftermarket parts such as electronic control modules (ECMs or “tuners”), has prompted CARB to revisit its existing regulations, which were created in 1977 and last updated in 1990. Following a public hearing on July 23, 2020, CARB adopted its new “Procedures for Exemption of Add-on and Modified Part(s) for On-Road Vehicles/Engines,” which will become effective in 2021. CARB has not yet published its final statement of reasons or a formal regulatory order in support of these changes.

New Procedures and Process

CARB’s recently adopted procedures are intended to update, clarify, and streamline its aftermarket parts approval process. The new procedures include updated language that better aligns with contemporary industry terminology and practices, and are organized into 10 sections describing the application process:

  • Applicability
  • Definitions
  • Application Submission Requirements
  • Evaluation and Testing Criteria
  • Test Vehicle or Engine Selection and Testing
  • Criteria for Category I Application Requests
  • Action of Application
  • Labeling Requirements
  • Issuing an Exemption Executive Order
  • Audit Testing

Starting in 2021, for EO requests other than the most simple administrative applications, the process envisioned by CARB will include a letter of intent, the identification of a specified aftermarket part category, a more narrow application of the vehicle or engine coverage for each EO, and new laboratory reporting requirements for the submission of emissions testing results.

Letter of Intent

Manufacturers are encouraged to send CARB a letter of intent by January 30 of each year, providing the manufacturer’s proposed device submissions over the 12 months to follow. According to CARB, this will allow the agency to advise on the best approach for the planned submissions and testing before the manufacturer begins.

Selection of One Part Category

CARB’s recently adopted procedures also include nine specific categories of aftermarket parts, and a manufacturer must choose one that best describes the part or request for exemption. If an application is outside the scope of the selected category, CARB will redirect the application to the appropriate category. The procedures list the minimum information that must be included in applications for each specific category, as well as evaluation and testing criteria for each specific category, consistent with their technological requirements.

The nine categories are as follows:

  • Category I – Part Number(s) or Name Change(s), Model-Year Additions on Carryover Vehicle(s) or Engine(s), Private Label(s), Extending Coverage to Subsidiaries, or Consolidation of Executive Orders
  • Category II – Air Intake Kits or Modifications
  • Category III – Engine Control Module (ECM) Programmers or ECM Signal Modifications
  • Category IV – Fuel Tanks or Fuel Tank Modifications
  • Category V – Intercooler Kits, Intercooler Components or Modifications
  • Category VI – Supercharger and Turbocharger Kits or Modifications
  • Category VII – Pre-Catalyst Exhaust Components
  • Category VIII – Other Categorized Parts
  • Category IX – Add-On or Modified Part(s) Not Covered by Categories II through VIII

Vehicle or Engine Coverage Requirements

The new approval process limits vehicle or engine coverage for each exemption application. Except when combined under the same test group or engine family, an application can only cover aftermarket parts that share the same single original equipment vehicle or engine manufacturer, vehicle or engine class, engine configuration, fuel type, emissions control technology, and emission standards. This is a departure from the current rules, which allow manufacturers to propose a scope of coverage from which CARB can then determine a “worst case” vehicle or engine for testing.

Test Vehicle or Engine Selection and Testing

Manufacturers still must be able to test under worst-case test parameters and demonstrate that either the test vehicle or engine with the device complies with applicable emissions standards or the modified emissions test results remain within 10% of a comparable (baseline) vehicle without the aftermarket part installed. CARB retains discretion to require alternate emissions, functional, or bench testing if it determines that the emissions testing is not adequate to characterize the emissions performance or durability of the part for which an exemption is sought.

Uniform Laboratory Reports

Unlike the previous rules, the recently adopted procedures set out the minimum information a laboratory report must contain, as well as how each report must be formatted.

Exemptions for Administrative or Less Complicated Requests

Because certain administrative (Category I) requests are deemed less complicated and do not allow fit, function, or design changes except when cosmetic (e.g., part number or name changes, model-year additions on carryover vehicles or engines, private labels or extending coverage to subsidiaries, and consolidation of EOs), in most cases the new procedures allow these to be processed based on engineering analysis and submitted information.


CARB promulgated these new procedures to update, clarify, and streamline the process by which manufacturers seek EOs for aftermarket parts. CARB clearly believes it will benefit from the new process, and certain manufacturers may benefit as well. However, for manufacturers with diverse product lines and parts that fit on a range of vehicles, the process is likely to increase the number of applications submitted and increase administrative and testing demands.

Ultimately, the true extent of the benefits and burdens of CARB’s new procedures for aftermarket parts approvals will not be realized until the process is fully implemented in 2021. Advanced planning by manufacturers could reduce the overall burdens and minimize the potential for adverse impacts.

For additional information, please visit CARB’s website.


If you have questions or would like more information on the issues discussed in this LawFlash, please contact any of the following Morgan Lewis lawyers:

Los Angeles
Rick R. Rothman
David K. Brown
Brittany M. Johnson

San Francisco
Ella Foley Gannon

[1] There are other exemptions for original equipment manufacturer (OEM) or equivalent replacement parts and parts that are installed on purely racing vehicles that may never be used, registered, or licensed for street use.