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On-Road Truck Grants & Regulation Information

Information updated June 10, 2021.

This information is intended as a general guide for San Luis Obispo County heavy-duty truck owners. Grant program and regulatory compliance is primarily dictated by state guidelines and emission regulations.  As such, for specific questions, please contact the state directly using the resources found near the end of this document.  Do not rely on this document as your only resource to determine your truck’s compliance.

The San Luis Obispo County Air Pollution Control District (APCD) is the local agency responsible for regulating stationary sources of air pollution such as paint and body shops, oil refineries and gas stations.  The California Air Resources Board (CARB) regulates emissions from mobile sources such as cars, trucks and off-road equipment.  The APCD administers grant programs that assist businesses to purchase mobile equipment that reduce emissions and comply with CARB regulations.  However, with the exception of school buses, APCD does not currently have incentive grants available for on-road trucks.

Why doesn't APCD provide truck funding? 

When we award an on-road grant project, we compare the emissions generated by the new and old truck and “buy” the emission reduction benefits from the project.  However, we can only pay for emission reductions that happen before the CARB Truck & Bus Regulation compliance deadline for the old truck.

The grant program guidelines from CARB require that truck replacement projects be completed at least one year before the old truck’s compliance deadline.  Because there is either no time or very little time before the emission deadlines for most trucks, APCD found that the eligibility and award amounts for trucks are severely limited, making the truck replacement funding category no longer viable.

Can I keep using my old truck?

With few exceptions (listed below), if your truck has a model year 2006 or older engine, the Truck and Bus Regulation prohibits its operation in the state.  See below for possible exceptions to these rules. Model years 2007 through 2009 must comply with the 2010 (or newer) emission standards by January 1, 2023, or be retired, as shown in the compliance table below.

Since 2019, trucks have been required to demonstrate compliance with the CARB Truck & Bus Regulation in order to renew registration with the DMV.


There are some exceptions to the general rules and the Engine Model Year Schedule. Exercising these exceptions require registration with and annual reporting to CARB:

  • Low-use vehicles that report annually to CARB and operate 1,000 miles or less in California are exempt from the PM filter and engine replacement rules.
  • The NOx-Exempt Area Extension allows vehicles that are equipped with a PM filter to operate indefinitely in the NOx-Exempt areas of the state.  Vehicle labeling and annual reporting is required. Our local NOx-Exempt area includes Santa Barbara, San Luis Obispo, Monterey, Santa Cruz and San Benito Counties.
  • To learn more about Truck & Bus Regulation compliance requirements and the above special provisions, see the CARB Truck & Bus Regulation Compliance Requirements Overview: https://ww3.arb.ca.gov/msprog/onrdiesel/documents/fsregsum.pdf

What is the NOx-Exempt Area Extension?

In areas of California like ours that have better air quality, the state allows trucks that are equipped with PM filters to operate indefinitely – that is, they are not required to retire the engine or comply with the 2010 (or newer) emission standards.  To use this option, the truck must stay in the NOx-Exempt areas of the state, must be reported annually to CARB, and must be labeled “NE” on both doors.  Our local NOx-Exempt area includes Santa Barbara, San Luis Obispo, Monterey, Santa Cruz and San Benito Counties.  According to the current Truck & Bus Regulation, NOx-Exempt vehicles can operate in NOx-Exempt areas indefinitely. For more information on the NOx Exempt Area Extension, see the CARB Fact Sheet: https://ww3.arb.ca.gov/msprog/onrdiesel/documents/fsnoxexempt.pdf

Can I retrofit my old truck?

Yes.  Retrofits (that is, aftermarket PM filters) are typically only installed on the heavier trucks because they are too expensive to be cost-effective for the 14,001 – 26,000 lb. trucks (it’s usually cheaper to replace the truck).  If your truck is currently non-compliant, a retrofit may bring it into compliance, but will not necessarily correct past violations.  We recommend you consult with CARB before retrofitting.  Retrofit equipment must be verified by CARB for your particular engine application.

Can I repower my old truck?

Repowering (replacing the engine with a 2010 or newer model year) is usually cost-prohibitive because of the extensive alterations to the truck that are required (for example, cooling, exhaust and electronics systems).  As with retrofitting, a repower may bring your truck into compliance, but will not necessarily correct past violations.  We recommend you consult with CARB before repowering your truck.

Is there financial assistance available to help me comply?

The state has a loan-guarantee program to help small businesses that need to bring their truck into compliance but may have trouble qualifying for a loan; it’s called Cal-Cap: treasurer.ca.gov/cpcfa/calcap/arb/index.asp

Where can I get more information?

For more information on the Truck & Bus Regulation, compliance options, reporting and contacting CARB, visit CARB’s “Truck Stop” web site: arb.ca.gov/msprog/truckstop/truckstop.htm
Or call the CARB diesel hotline: 1-866-6DIESEL