California Air Resources Board

The goal of the In-Use Off-Road Diesel-Fueled Fleets Regulation is to reduce particulate matter (PM) and oxides of nitrogen (NOx) emissions from in-use (existing) off-road heavy-duty diesel vehicles in California.  The regulation covers a wide scope of vehicle types used in (but not limited to) industries as diverse as construction, air travel, manufacturing, landscaping, and ski resorts. 

​Background

The California Air Resources Board (CARB) approved the Off-Road Regulation (Cal. Code Regs., tit. 13, §§ 2449 et seq.) for adoption in 2007, and it became effective in 2008. The Off-Road Regulation was amended twice in 2009, and again in 2010. The 2009 amendments introduced additional credits to incentivize early actions and added clarifying language. The 2010 amendments made significant changes to the Off-Road Regulation which delayed the initial compliance date for all fleets by four years, provided a path to compliance without any required retrofits, and simplified the Off-Road Regulation. The purpose of the Off-Road Regulation is to reduce diesel PM, NOx, and other criteria air pollutants from in-use off-road heavy-duty vehicles in California.

In November 2022, CARB approved amendments to the Off-Road Regulation that are effective October 1, 2023. These amendments were one of several measures identified for action by CARB as part of the 2022 State Strategy for the State Implementation Plan. These amendments will achieve additional NOx and PM reductions and enhance the enforceability of the Off-Road Regulation.

General Requirements

The Off-Road Diesel Regulation:

• Imposes limits on idling, requires a written idling policy, and requires a disclosure when selling vehicles;
• Requires all vehicles to be reported to CARB, which can be done through the online reporting system DOORS, and labeled;
• Restricts the adding of older vehicles into fleets starting on January 1, 2014;
• Requires fleets to reduce their emissions by retiring, replacing, or repowering older engines, or installing Verified Diesel Emission Control Strategies, VDECS (i.e., exhaust retrofits);
• Requires the phase-out of the oldest and dirties engines starting on January 1, 2024;
• Requires the procurement and use of renewable diesel (R99 or R100) starting January 1, 2024, with limited exceptions; and
• Requires contracting entities to obtain valid Certificates of Reported Compliance for all listed contractors and subcontractors for contract work where vehicles subject to the Off-Road Regulation will operate.

The Off-Road Diesel Regulation has additional requirements not listed above, the regulatory text contains the full requirements of the regulation. 

Reporting

Off-road diesel vehicle owners are required to report their applicable diesel vehicles to CARB. CARB provides an easy-to-use online reporting tool, DOORS, to help fleets complete this requirement.

Beginning in 2009, all applicable off-road diesel vehicles were required to be reported to CARB. When a diesel vehicle is reported in DOORS, the vehicle is assigned a unique equipment identification number (EIN). The vehicle must be labeled within 30 days of receiving this EIN. You can learn more about labeling and reporting in DOORS on the DOORS Resources page. This page contains user guides and training videos to help you report in DOORS.

DOORS Reporting System
DOORS Resources

Frequently Asked Questions

View the Regulation FAQ page for documents addressing the most frequently asked questions.

Forms

View the Regulation Forms page for current forms.