California Air Resource Board (CARB) Emissions Regulations

What is the CARB truck and bus regulation?

The CARB truck and bus regulation, also known as the In-Use On-Road Heavy-Duty Diesel Vehicles Regulation, requires upgrades to trucks and buses running on diesel fuel and operating in California to reduce emissions of diesel particulate matter and oxides of nitrogen. 

Nearly all privately and publicly owned on-highway diesel vehicles with a gross vehicle weight of over 14,000 lbs. must comply with the regulation while operating in California. Diesel particulate matter filter retrofits for heavier trucks are already required. Requirements for all vehicles subject to the regulation will phased in until 2023, when all applicable vehicles will be required to have a 2010 model year engine or newer.

Numerous credits, exemptions, and exceptions apply to the phase-in schedule. For a complete summary of the regulation, download CARB's pdf.

Compliance and Reporting Guidelines

CARB regulations are complex, and determining your compliance deadline - and what is required of your fleet to meet requirements - can be difficult. CARB offers a Fleet Calculator to help you determine the requirements for your fleet.

Additionally, fleet owners operating in California must submit details on their vehicles to CARB. With some exceptions, this is a current requirement for vehicles over 26,000 lbs GVWR. Vehicles between 14,000 and and 26,000 lbs GVWR must be reported by Jan. 1, 2015. Benefits may be available for fleet owners who report their vehicles early. For details on how to report, along with tools for reporting online or by mail, visit CARB's website.

We're Here to Help!

If you need help in determining which CARB regulations apply to your fleet or information on the technology that's currently available to reduce your diesel vehicle's emissions, contact our emissions specialist:

Gary Galindo


Truck and Bus Regulation Summary (pdf)
Additional Fact Sheets
Calculate Your Fleet's Requirements
How to Report to CARB