When a product is CARB certified, it has been tested and approved by the California Air Resources Board as meeting California’s emission and air quality standards, which are the strictest in the United States. The label applies to far more than cars: lawn equipment, gas cans, aftermarket engine parts, composite wood flooring and furniture, and indoor air purifiers all fall under CARB’s rules. Because more than a dozen other states have adopted California’s vehicle standards, a CARB certification affects what you can buy and register well beyond California’s borders.
What CARB Is and Why Its Approval Carries Weight
The California Air Resources Board is the state agency responsible for regulating air pollution in California. Federal law generally prevents states from writing their own vehicle emission rules, but California is a specific exception. Under 42 U.S.C. § 7543, the EPA can grant California a waiver to enforce standards stricter than federal ones, as long as they are at least as protective of public health.1Office of the Law Revision Counsel. 42 U.S. Code 7543 – State Standards
That waiver is what gives a CARB certification its authority. When CARB approves a product, the approval carries the force of state law in California and, through adoption by other states, in a large share of the national market.
Products That Need CARB Certification
The category matters, because the certification looks a little different for each type of product.
New Vehicles and Motorcycles
Every new passenger car, light-duty truck, medium-duty vehicle, and motorcycle sold in California must be CARB certified. The program also covers off-highway recreational vehicles like ATVs and side-by-sides.2California Air Resources Board. On-Road Light-Duty Vehicle Certification Program For diesel trucks and buses over 14,000 pounds, California’s Truck and Bus Regulation requires a 2010 or newer model year engine and emission system to operate in the state, and the DMV will deny registration to vehicles that don’t comply.3California Air Resources Board. Truck and Bus Regulation
Aftermarket Auto Parts
Any add-on or modified part that touches a vehicle’s emission system needs CARB approval before it can legally be sold or installed in California. CARB engineers test the part to see whether it raises emissions; if it doesn’t, CARB issues an Executive Order exempting it from California’s anti-tampering laws.4California Air Resources Board. Aftermarket, Performance, and Add-on Parts This is where verification matters most for the average consumer. Catalytic converters, cold air intakes, and engine management chips without a valid Executive Order can cause a Smog Check failure.
Small Off-Road Engines
Spark-ignition engines rated at or below 19 kilowatts, the kind used in lawn mowers, leaf blowers, and chainsaws, fall under CARB’s Small Off-Road Engine program. A regulation adopted by CARB requires most newly manufactured small off-road engines to be zero-emission starting in 2024, with portable generators and large pressure washers moving to zero-emission standards in 2028.5California Air Resources Board. CARB Approves Updated Regulations Requiring Most New Small Off-Road Engines Be Zero Emission by 2024 The rules apply to new equipment sold in California, not to gear already in use.
Composite Wood Products
Particleboard, medium-density fiberboard, and hardwood plywood release formaldehyde gas from the adhesives used to make them. CARB’s Phase 2 standards cap those emissions, and the federal EPA later adopted the same limits under TSCA Title VI.6U.S. Environmental Protection Agency. Formaldehyde Emission Standards for Composite Wood Products California’s rules go further on labeling: all composite wood products and finished goods sold in California need a label, while the federal rule exempts finished goods under 144 square inches. Products made with no-added-formaldehyde or ultra-low-emitting resins can be labeled “NAF” or “ULEF.”7California Air Resources Board. Frequently Asked Questions: Labeling
Indoor Air Cleaning Devices
Electronic air purifiers and in-duct air cleaners sold in California must be CARB certified for electrical safety, and electronic models must be tested for ozone emissions, which cannot exceed 50 parts per billion.8California Air Resources Board. Air Cleaner Information for Manufacturers Some ionizers and ozone generators marketed as air cleaners can produce ozone levels that worsen indoor air rather than improve it, which is why the certification exists in this category.
Portable Fuel Containers
Gas cans sold in California must meet certification requirements aimed at cutting hydrocarbon vapor emissions. The spout has to close automatically when removed from the tank, seal completely when not in use, and the container can have only one opening for both filling and pouring. Containers made since 2009 must emit no more than 0.3 grams of total organic gases per gallon per day and be color-coded: red for gasoline, yellow for diesel, blue for kerosene, with the fuel type labeled in at least 34-point font.9California Air Resources Board. Certification Procedure for Portable Fuel Container Systems CP-501
The Executive Order: What Certification Actually Looks Like
The tangible form of a CARB certification is a document called an Executive Order, or EO. Every approved product receives an EO number in an alphanumeric format, such as “D-193-140.” The letter indicates what the part regulates, the middle number identifies the manufacturer, and the final number is the specific order for that product.4California Air Resources Board. Aftermarket, Performance, and Add-on Parts
The Executive Order also specifies which vehicles, engines, or equipment the certification covers. A part with a valid EO installed on a vehicle outside the covered list is not, in practice, CARB certified for that use.
How to Verify a Product Is CARB Certified
Start with the product itself. CARB-certified items generally carry a label or sticker showing the Executive Order number.
- On vehicles, look under the hood or on the engine for the emissions label.
- On lawn and outdoor equipment, check the engine housing or the product packaging.
- On composite wood products, look for a label on the back of the piece or inside a cabinet door. It should list the fabricator’s name, the date of production, and a statement of compliance with CARB Phase 2 standards. A label that reads “TSCA Title VI compliant” also meets California’s labeling requirement.7California Air Resources Board. Frequently Asked Questions: Labeling
- On aftermarket auto parts, ask the seller for the EO number before you buy.
Then confirm it with CARB. The agency publishes searchable databases on its website, organized by product category, where you can look up Executive Orders by manufacturer, product type, or EO number.10California Air Resources Board. Executive Orders, Certifications, and Verifications Air purifiers have their own list, searchable by brand and model.11California Air Resources Board. List of CARB-Certified Air Cleaning Devices Smog Check stations and Bureau of Automotive Repair referee stations can also verify EO numbers during vehicle inspections.4California Air Resources Board. Aftermarket, Performance, and Add-on Parts
If a seller cannot produce an EO number for a part that should have one, or if the number doesn’t appear in CARB’s database, treat the product as uncertified.
Why CARB Certification Matters Outside California
Under Section 177 of the Clean Air Act, other states can adopt California’s vehicle emission standards as their own.12California Air Resources Board. States That Have Adopted California’s Vehicle Regulations As of 2025, roughly 17 to 18 states plus the District of Columbia have adopted at least some of California’s light-duty vehicle standards, including Colorado, Connecticut, Maryland, Massachusetts, New Jersey, New York, Oregon, Virginia, and Washington. A smaller group of about 11 states has adopted California’s Advanced Clean Trucks standards.13Alternative Fuels Data Center. Adoption of California’s Clean Vehicle Standards by State
If you live in one of those states, the vehicles at your dealership already reflect CARB rules, and aftermarket parts that lack a CARB EO may not be legal to install even though you’re outside California.
What Happens When a Product Isn’t Certified
For vehicles and parts, the enforcement point most consumers hit is the Smog Check. California requires a Smog Check to register a vehicle in the state for the first time, including vehicles purchased out of state, and every other year for registration renewal. Aftermarket parts without CARB approval will cause a failure, as will engine control software that has been modified away from the manufacturer’s original settings or a CARB-approved alternative.14Bureau of Automotive Repair. Smog Check: When You Need One and What’s Required
For heavy-duty trucks and buses that don’t meet the Truck and Bus Regulation, the DMV may issue a 90-day Temporary Operating Permit so the owner can bring the vehicle into compliance or replace it. The permit is a final window rather than an extension, and citations are still possible during that period. Anyone selling a non-compliant vehicle must give the buyer a written disclosure on the bill of sale or sales contract.15California Air Resources Board. CARB Warning on DMV Registration Renewal Notice
Penalties on the manufacturer side are steep. For new motor vehicle and engine certification violations, fines can exceed $47,000 per action, with per-unit penalties reaching nearly $12,000. A single non-verified diesel emission control device can carry fines of up to $5,000 per unit, with daily penalties reaching $10,910.16California Air Resources Board. Engine Manufacturer Cummins Settles California Certification Procedure and Emissions Violations Case for $46 Million That enforcement is what stands behind the label on the product in your hand, and it’s why taking a few minutes to check an EO number in CARB’s database is worth the effort before you buy.