California Air Resources Board

The Verification Procedure, Warranty and In-Use Compliance Requirements for In-Use Strategies to Control Emissions from Diesel Engines (Verification Procedure) was created and adopted by our Board on May 16, 2002. The goal of the Verification Procedure is to ensure real emission reductions, along with an emission control system that is durable and compatible with various engines and applications. All applicants should be aware that as part of the Verification process, it is the applicant’s responsibility to provide data to verify emission reduction claims. This includes specific laboratory testing for which the applicant bears the total cost, along with robust in-use testing which is required after the diesel emission control devices have been in operation for a certain period of time.  Annual warranty reporting is also required by each manufacturer, for each of their verified products.

What's the difference between Verification and Certification?

CARB has several programs relating to sale, use, or modification of emission control systems. The programs are specific to the type of device as well as the market for which it was designed. The information below outlines the various programs. An exemption is necessary for the sale of aftermarket parts if they are to be sold or used in California: To improve air quality, CARB requires vehicle manufacturers to develop engine and emission equipment systems that reduce the specific pollutants that cause California's severe air quality problem.

These emission control systems are also required to be proven durable and reliable. To ensure that these systems operate as designed, California Vehicle Code Section 27156 and the Federal Clean Air Act prohibit modifications to these systems that increase motor vehicle emissions. Since if properly designed, most performance modifications do not increase vehicle emissions, these same laws also allow the installation of parts or modifications proven by their manufacturers and certified by CARB not to increase vehicle emissions. Visit Aftermarket Parts for more Information on the exemption and other aftermarket parts related programs.

The Verification Procedure provides a way to thoroughly evaluate the particulate matter (PM) and oxides of nitrogen (NO_x) emission reduction capabilities and durability of a variety of diesel emission control strategies as part of a retrofit in-use program. It ensures that emission reductions achieved by a control strategy are both real and durable and that production units in the field are achieving emission reductions which are consistent with their verification. The verification program supports CARB's Diesel Risk Reduction Plan.

Certification requires that new motor vehicles and engines must be certified by CARB for emission compliance before they are legal for sale, use, or registration in California. Certification is granted annually to individual engine families and is good for one model year. An engine family is a grouping of vehicles or engine models that exhibit similar emission characteristics (e.g., common engine parameters, fuel system, and emission control systems). Within an engine family, there may be one or more evaporative families that are associated with distinct vehicle models.

Federal Programs

U.S. EPA's Voluntary Diesel Retrofit Program: U.S. EPA has developed the Voluntary Diesel Retrofit Program to help make a difference in the immediate future. The program will address pollution from diesel construction equipment and heavy-duty vehicles that are currently on the road today.

U.S. EPA's Environmental Technology Verification (ETV) Program develops testing protocols and verifies the performance of innovative technologies that have the potential to improve protection of human health and the environment. ETV was created to accelerate the entrance of new environmental technologies into the domestic and international marketplace.