CARB Emission Regulations for Trucks Operating in California

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Peach State Truck Centers Take every measure to validate information we publish, however information around this particular topic is subject to change so please make sure you’re following official sites and documentation for the latest information

What is CARB?

CARB is the California Air Resources Board, and they are charged with protecting the public from the harmful effects of air pollution and developing programs and actions to fight climate change in the state of California. From requirements for clean cars and fuels to adopting innovative solutions to reduce greenhouse gas emissions, California has pioneered a range of effective approaches that have set the standard for effective air and climate programs for the nation, and the world.

What are CARB regulations?

The California Air Resources Board (CARB) regulations are intended to reduce emissions from vehicles, fuels, and other sources operating in California to improve air quality and public health. The state of California is working to adopt and implement regulations around commercial vehicles driven in California. CARB regulations are complicated, not always clear, and subject to change. The Board continually updates and revises its regulations to address emerging challenges and advance its goals of improving air quality and reducing emissions; so, be sure to review multiple sources and note the dates the information was published.

Below are highlights of the new CARB regulations that affect any vehicle that operates or drives in or through California. Most of what you see below is taken directly from the CARB website to make this document as accurate as possible.

Who is affected?

High Priority Fleet - High priority fleets are entities that own, operate, or direct the operation of at least one vehicle in California, and that have either $50 million or more in gross annual revenue, or that own, operate, or direct the operation of a total of 50 or more vehicles.

New CARB regulations

CARB regulations have changed. In order to comply with CARB’s new regulations (as of January 2024), affected fleet owners have two options: following the Model Year Schedule or choosing the ZEV (Zero Emission Vehicle) Milestone Option.

Model Year Schedule

Beginning January 1, 2024, fleet owners may add only zero emission vehicles (ZEV) to their California fleet; includes those vehicles operated in California by a fleet owner or controlling party during a calendar year and includes those vehicles under common ownership or control. 

Beginning January 1, 2025, fleet owners must begin removing internal combustion engine (ICE) vehicles from their California fleets by January 1st of the calendar year after those vehicles exceed their minimum useful life mileage thresholds, or January 1st of the calendar year the engine model year is 18 years old or older, whichever occurs first. Starting in 2024, any new ICE vehicle, 2024 or newer, added to the California fleet must have an engine certified to applicable California emissions standards and emissions related requirements, and any used ICE vehicle added to the California fleet must have a 2010 or newer model year engine.

--- OR ---

ZEV Milestone Option

Until January 1, 2030, instead of the Model Year Schedule, fleet owners may elect to meet ZEV targets as a percentage of their California fleet starting with vehicle types that are most suitable for electrification. This option allows for phasing ZEVs into the fleet between 2025 and 2042 based on the vehicle type. When opting into the ZEV Milestones Option, the fleet owner must report this intention.  

When do the new CARB regulations go into effect?

The new CARB regulations affect engines built on or after January 1, 2024. Note that the engine model year is the guide, not the truck model year.

What are the new CARB reporting requirements?

The first compliance requirement is to submit a compliance report--the initial report must be submitted by February 1, 2024. Fleet owners must annually submit a compliance report for their California fleet, as it is composed as of January 1 of the corresponding calendar year.

Common Acronyms & Terms Glossary

ACF – The Advanced Clean Fleets Regulation requires fleets that are well suited for electrification to transition to zero-emission vehicles (ZEV) through requirements to both phase-in the use of ZEVs for targeted fleets and requirements that manufacturers only manufacture ZEV trucks starting in the 2036 model year.  

ACT – The Advanced Clean Trucks regulation is a manufacturers ZEV sales requirement and a one-time reporting requirement for large entities and fleets.  

CARB – The California Air Resources Board (CARB) is responsible for regulating air quality and implementing measures to reduce air pollution in California. 

g/bhp-hr – Grams per brake horsepower – hour.  A standard of measure commonly used by the EPA and CARB to measure emissions from an engine

High Priority Fleet - High priority fleets are entities that own, operate, or direct the operation of at least one vehicle in California, and that have either $50 million or more in gross annual revenue, or that own, operate, or direct the operation of a total of 50 or more vehicles (currently interpreted as the total US fleet, not just CA). 

NOx - Nitrogen Oxides are a family of poisonous, highly reactive gases which form when fuel is burned at high temperatures. Ground-level ozone (the main ingredient in smog) is formed by a chemical reaction between VOCs and NOx in the presence of sunlight. Ozone concentrations can reach unhealthful levels when the weather is hot and sunny with little or no wind. 

Omnibus NOx – California’s Nitrogen Oxide (NOx) emissions standard set by the Heavy-duty Omnibus regulations for new California-certified 2024 through 2026 model year engines which is 0.050 g/bhp-hr.  

ZEV - Zero Emission Vehicle (electric)

Again, as these regulations are ever changing, be sure to stay up to date on CARB regulation updates, as well as which laws in California apply to the new CARB regulations.

Where can I learn more and stay up to date?

CARB Heavy Duty Omnibus Regulation Page

CARB Low-Nox Page 

CARB Low Nox Fact Sheet

Register for e-mail updates directly from CARB