Application Forms for Exemptions for Add-On or Modified Parts (VC 27156)

This page last reviewed October 3, 2019

Manufacturers of add-on and modified parts planning to sell their product for use in California vehicles should apply for an exemption from Vehicle Code Section (VC) 27156. A VC 27156 exemption is granted if the product has been determined not to cause any increase in vehicular emissions. The first step to obtain a VC 27156 exemption is to submit an application to the Air Resources Board. There are three types of forms available; a manufacturer must fill out the form appropriate for its product. Each form is available by clicking the associated link, below.

Form A -

General Criteria Parts Application: this must be filled out for those add-on and modified parts for which vehicle or engine emission testing may be required to determine their impact on emissions.

Form B -

Compliance Criteria Parts Application: this must be filled out for those parts for which explicit criteria are satisfied in writing, and which do not require vehicle or engine emission testing to obtain the VC 27156 exemption. Parts eligible for compliance criteria evaluation are exhaust headers for non-feedback controlled catalyst-equipped vehicles, intake manifolds for non-EGR vehicles only, ignition system components excluding distributors), ignition distributors, and intercoolers.

Form C -

Application for Turbochargers / Superchargers: this must be filed for systems which include a turbocharger or supercharger.

Once the application has been filed, the Air Resources Board will contact you to inform you of missing information or to specify test vehicles. You are responsible for obtaining the vehicles and having them tested at a qualified independent laboratory. If you have any questions concerning the suitability of a vehicle for testing or the test themselves, please contact the staff engineer assigned to your application. If confirmatory testing is required at the Air Resources Board's laboratory after you completed the testing, you must provide the test vehicle, but there is no charge for testing.

Manufacturers must present sufficient information to establish that an emissions increase will not result from the use of an add-on or modified part. If your device or modification is exempted, the Air Resources Board will issue an Executive Order stating that the part will not adversely affect emissions and that it is legal for sale and use in California.

Please send the completed application along with the necessary attachments to:

Branch Chief
Aftermarket Parts Certification and Audit Branch
Emissions Compliance, Automotive Regulations and Science Division
Air Resources Board
9480 Telstar Avenue, Suite 4
El Monte, CA  91731