The truck runs on the highway. 3d render and illustration

New Requirements for Heavy-Duty Trucks in 2023

Categories: Trucking.

For years, California has led the way toward a more sustainable freight and transportation industry, and the state continues to push for a zero-emissions supply chain future. First up: The last replacement phase of the California Truck and Bus Regulation is here, with a deadline of January 1, 2023, to comply.

In effect since 2008, this regulation was developed by the California Air Resources Board (CARB) to reduce toxic air contaminants (TACs) emissions from truck exhaust, with the ensuing goal of lessening smog and safeguarding public health in disadvantaged communities. Under the regulation, older heavy-duty diesel vehicles with a gross vehicle weight rating (GVWR) greater than 26,000 pounds must be replaced with 2011-or-newer vehicles, or be retrofitted with 2010-or-newer model-year engines.

But that’s not the only thing changing for heavy vehicles in California. As of January 1, 2023, the Heavy-Duty Inspection and Maintenance Regulation (HD I/M) will begin its first phase.

The regulation dates to 2019, when California governor Gavin Newsom signed into law Senate Bill 210, which directed CARB to create and implement a comprehensive HD I/M program to better control emissions from non-gasoline on-road heavy-duty vehicles. In consultation with the Department of Motor Vehicles and the Bureau of Automotive Repair, the resulting program aims to reduce toxic emissions and protect the communities most affected by air pollution.

What’s the goal of the HD I/M program?

Overall, the goal of the HD I/M regulation is to lower emissions, improve air quality and, subsequently, reduce the impact of pollution on public health.

“HD I/M will ensure that the emissions control equipment in heavy-duty trucks does its job capturing and removing harmful emissions for the life of the vehicle,” says Liane Randolph, CARB Chair. “And, if we discover it’s not working properly, it will be repaired quickly. This will save owners and operators in fuel costs and deliver significant improvements in air quality and public health, especially in communities adjacent to highways, ports, and warehouses that suffer from persistent air pollution as a result of heavy traffic.”

Trucks — particularly heavy-duty trucks — produce a significant amount of particulate matter (PM) and nitrogen oxide (NOx) emissions. And although these vehicles make up just 3% of California’s total on-road vehicle fleet, they emit about 52% of the state’s on-road NOx emissions, and about 54% of the on-road PM 2.5 emissions.

These emissions pollute the air with carcinogenic TACs, contribute to acid rain, and can lead to serious negative health consequences, including asthma and cardiopulmonary and respiratory disease.

Modern trucks often come standard with aftertreatment systems that minimize emissions. However, anywhere from 11 to 17% of them have malfunctioning emissions control systems, and older vehicles don’t have these systems at all.

The California Truck and Bus Regulation ensures these older trucks will be off the road by January 1, but HD I/M will roll out to ensure the aftertreatment systems in newer vehicles are consistently and properly maintained and repaired.

Ultimately, HD I/M is expected to be one of the most impactful CARB programs approved in decades. It’s projected to reduce 8.6 tons per day (tpd) NOx and 0.09 tpd PM emissions in San Joaquin Valley in 2024, and to cut California’s NOx emissions by 81.3 tpd and PM emissions by 0.7 tpd by 2037. This would mean avoiding some 7,500 premature deaths and 6,000 hospitalizations statewide — health benefits totaling $75.8 billion for 2023-2050.

What does the program entail?

The HD I/M program applies to all non-gasoline on-road heavy-duty trucks with a GVWR greater than 14,000 pounds, and aims to ensure that emissions control systems on these vehicles are in working order.

Similar to how non-commercial drivers must bring in their cars for periodic smog checks, heavy-duty truck drivers will be required to perform recurrent emissions testing to show compliance.

The HD I/M regulation will be implemented in three main phases:

  • Starting this January, Portable Emissions Acquisition Systems (PEAQSs) — which were recently debuted at a CARB event at the Port of Los Angeles — will be deployed on roadsides to screen for high-emitting vehicles. Trucks flagged by the system as potentially non-compliant will need to undergo emissions testing.
  • Beginning in July 2023, all heavy-duty trucks will need to obtain a certificate of compliance from CARB, which will allow them to legally operate in California.
  • Beginning in January 2024, heavy-duty vehicle operators will be required to pass two emissions tests per year to maintain both compliance and DMV registration.

Additionally, starting in 2027, trucks with onboard diagnostic [OBD] systems must increase testing to four times per year, while older heavy-duty vehicles without an OBD system will continue the twice-yearly testing requirements, with an added visual testing component.


As the freight and transportation industry progresses toward a more sustainable future, we expect to see even more regulatory requirements proposed and put into effect over the next few years. Stay ahead of the curve and future-proof your business by partnering with an experienced 3PL like GlobeCon.

Need a reliable partner at the ports of Los Angeles and Long Beach? Contact GlobeCon today.