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Commentary: State air board intensifies enforcement of ‘truck rule’

Issue Date: August 21, 2019
By Noelle Cremers
Noelle Cremers
State air-quality rules requiring truck owners to replace diesel engines have been phased in, with final compliance scheduled by Jan. 1, 2023.
Source: California Air Resources Board
Photo of Truck
State air-quality rules requiring truck owners to replace diesel engines have been phased in, with final compliance scheduled by Jan. 1, 2023.
Source: California Air Resources Board

Truck owners, be ready: Starting next January, you won't be able to register your truck with the state Department of Motor Vehicles if it's not in compliance with air quality regulations.

Here's the background. In 2008, California adopted an extensive regulation intended to reduce emissions from heavy-duty diesel vehicles, known as the Diesel Truck and Bus Rule. The rule has been phased in during the time since then, with compliance timing depending on the weight, age and use of the truck.

Heavy-duty diesel trucks are generally subject to the rule if they have a Gross Vehicle Weight Rating, or GVWR, of more than 14,000 pounds and are designed for on-road use, regardless of whether they are actually driven on the road. By 2023, all trucks subject to the rule will have to be upgraded or replaced with an engine from the 2010 model year or newer. There is an exception for low-use trucks—those driven less than 1,000 miles each year, with owners reporting mileage annually to the California Air Resources Board.

The Air Resources Board has been undertaking an extensive enforcement campaign. It has sent thousands of non-compliance letters to owners of trucks who the ARB says are not complying with the Truck and Bus Rule. Soon, an additional enforcement mechanism will take effect.

Starting Jan. 1, 2020, trucks that are not in the ARB database as compliant will not be able to be registered with the DMV. Anyone with a diesel truck subject to the rule should make sure the truck is in compliance, prior to going to the DMV to register the truck.

Trucks used exclusively in agriculture that were registered with the ARB by January 2015 are eligible for an agricultural compliance option. These trucks can remain in use until Jan. 1, 2023, so long as they are driven less than 10,000 miles annually, with those miles reported to the ARB by Jan. 31 each year.

Some diesel vehicles are specifically exempt from the Truck and Bus Rule. Exempt vehicles include snow-removal vehicles, personal-use motor homes or recreational vehicles, and pickup trucks driven exclusively for personal use that are between 14,001 and 19,500 GVWR. For a pickup truck to be eligible for the exemption, it cannot be used for any commercial purpose; if the truck is used for an activity that is intended to produce a profit, it is not eligible for this exemption.

The ARB has developed a system to enter these exempt vehicles into a database, so the DMV can easily see the vehicles are not subject to the Truck and Bus Rule and can be registered. Additionally, trucks that were converted from diesel to another fuel type, or a truck with a 2010 or older chassis that has a newer engine compliant with the rule, should also be entered into the ARB system. The Excluded Diesel Vehicle Reporting system is available on the ARB website at If you own one of these exempt vehicles, you would benefit from entering it into the ARB system, to help with DMV registration in 2020.

There's another wrinkle to complying with the rule: Certain California counties have attained air standards for oxides of nitrogen. Trucks in these NOx Exempt Areas may comply with the rule through installation of a particulate filter, or PM filter; by reporting annually to ARB that the truck is complying by meeting the NOx Exempt Area rules; and by being driven only within the NOx Exempt counties. Those counties are Alpine, Colusa, Del Norte, Glenn, Humboldt, Lake, Lassen, Mendocino, Modoc, Monterey, Plumas, San Benito, San Luis Obispo, Santa Barbara, Santa Cruz, Shasta, Sierra, Siskiyou, northern Sonoma, Trinity, Tehama and Yuba. If any trucks using this compliance option do not yet have PM filters installed, the ARB recommends those be ordered by September to ensure compliance by the Jan. 1, 2020, deadline.

California places numerous, costly and complicated regulations on businesses operating within the state. Certainly, the Diesel Bus and Truck Rule is one of those. To avoid the headache of showing up at the DMV to register your diesel truck and being told that you cannot, Farm Bureau recommends you work now to ensure your trucks are in compliance. Questions? Visit the ARB Truck Stop website at or contact me via email at

(Noelle Cremers is a policy advocate for the California Farm Bureau Federation.)

Permission for use is granted, however, credit must be made to the California Farm Bureau Federation when reprinting this item.

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