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On-Road Truck Grants & Regulation Information

Information updated April 10, 2019.

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 agricultural vehicles, school buses, and transit buses, APCD does not currently have incentive grants available for on-road trucks.

Why does APCD no longer have 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.

Why does APCD still fund agricultural trucks?

On-road vehicles engaged in “agricultural operations” (as defined by the ARB Off-Road Regulation) for over 50% of their annual operation may qualify for funding because the funds come from a different source: the Funding Agricultural Replacement Measures for Emission Reductions (FARMER) Program. This state program provides funding for agricultural harvesting equipment, heavy-duty trucks, replacement or electrification of irrigation engines, tractors, and other equipment used in agricultural operations.  These projects must still comply with the strict guidelines regarding the compliance deadlines.  The agricultural truck grant application is available here.

Can I keep using my old truck?

With few exceptions (listed below), if your truck is over 26,000 lbs. GVWR and has a model year 1996 or newer engine, it must be equipped with a particulate matter (PM) filter to operate in California.  If the engine is a model year 1995 or older, the Truck and Bus Regulation prohibits its operation in the state.  See below for possible exceptions to these rules.  Model years 1996 through 2009 have upcoming deadlines when they must comply with the 2010 (or newer) emission standards, or be retired, as shown in the compliance table for heavier vehicles below.

Generally (exceptions listed below), if your truck is 14,001 – 26,000 lbs. GVWR and has a model year 1999 or older engine, the Truck and Bus Regulation prohibits its operation in California.  The 2000 – 2009 model years have upcoming deadlines as shown in the compliance table for lighter vehicles below, when they will have to comply with the 2010 (or newer) emission standards or be retired.

Starting in 2019, trucks will have 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, which require registration with and annual reporting to CARB.  The first two special provisions below are more regularly used by SLO County trucks than the others:

  • 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.  Our local NOx-Exempt area includes Santa Barbara, San Luis Obispo, Monterey, Santa Cruz and San Benito Counties.
  • Vehicles using the Low-mileage Construction Truck Option are allowed a delay in complying with the 2010 (or newer) emission standards.
  • The Agricultural Vehicle Extension gives low-use ag vehicles until 2023 to comply, but the period to opt-in to this extension has passed.
  • To learn more about Truck & Bus Regulation compliance requirements and the above special provisions, see the CARB Truck & Bus Regulation Fact Sheets and Reporting Documents: arb.ca.gov/msprog/onrdiesel/documents.php


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, and must be reported to CARB and labeled “NE” on both doors.  Our local NOx-Exempt area includes Santa Barbara, San Luis Obispo, Monterey, Santa Cruz and San Benito Counties.  If you are replacing your older truck, using this option would allow you to replace it with a new or used truck, as long as it is equipped with a PM filter.  According to the current Truck & Bus Regulation, NOx-Exempt vehicles can operate in NOx-Exempt areas indefinitely.

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 14,000 – 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