In addition to the Advanced Clean Trucks update provided on Tuesday, April 8, several other actions are underway by the California Air Resources Board (CARB).
Please note that, while this Advanced Clean Truck article focused on multiple states, these updates below are specific to California and will cover:
- Low NOx Omnibus regulation
- Small Off-Road Engine (SORE) regulation
- Advanced Clean Fleets regulation
- Heavy-Duty Inspection/Maintenance program, now called Clean Truck Check
Low NOx Omnibus
In September of 2021, the California Air Resources Board (CARB) adopted the amended Omnibus Low NOx regulation which established more stringent NOx and Particulate Matter standards applicable to new 2024 and later Model Year medium- and heavy-duty diesel engines. The Environmental Protection Agency (EPA) waiver for this rule, which was granted on January 6, 2025, was submitted to Congress earlier this year for possible action under the Congressional Review Act (as has the Advanced Clean Trucks waiver granted in April of 2023). Under the Congressional Review Act, Congress can review and disapprove rules issued by federal agencies within a certain timeframe before the rules take effect. The Congressional Review Act can be invoked within 60 session days after a rule has been published and submitted to Congress. Legislation to repeal these waivers was introduced in the House last week; similar legislation is expected to be introduced soon in the Senate.
However, the Senate Parliamentarian, who determines what the Senate can and can’t do legislatively, said last week in a meeting with Senate staff that the waivers are not rules and thus can’t be overturned by Congress. She made clear when saying this that it was not an official ruling, but her thoughts on the issue at that time. The Senate could choose to overrule the Parliamentarian on a point of procedure, but it’s unclear if they will do so. If Congress does not act, EPA could move to withdraw the waiver through standard rulemaking, which would be a much more extensive process.
No matter which approach moves forward – legislative or regulatory – it will be likely subject to lawsuits from California, other states that follow California, and possibly environmental groups. The RV Industry Association will continue to monitor activities on this issue and report out to our members.
Small Off-Road Engine (SORE)
The small off-road engine regulation which was adopted in 2021 established new lower emissions limits for gasoline or propane engines smaller than 25 horsepower, which include portable generator engines (which CARB determined included generators mounted in RVs). However, due to the wildfires in the Los Angeles area at the beginning of the year, CARB will exercise maximum discretion with regard to the sale and use of new generators less than 19 kilowatts in size by temporarily allowing (through June 30, 2025) the import, distribution, sale, and offer for sale of U.S. EPA certified generators subject to certain conditions.
The small off-road engine rule also required portable generator engines to be completely zero-emissions (ZE) by Model Year 2028. CARB staff were directed to report annually on the status of compliance and the progress being made (or not being made) in developing zero-emission solutions. Staff were also directed to issue a more detailed technology readiness assessment in the 2025-2026 timeframe. If this readiness assessment finds that the technology needed for compliance in 2028 is unlikely to be available, consideration will be given to adjusting the timeline for zero-emission compliance for generator engines. The RV Industry Association will participate fully with CARB staff on this study and has communicated that the study should be undertaken soon.
Advanced Clean Fleets Regulation
The Advanced Clean Fleets rule would have required all medium- and heavy-duty vehicles sold into California, including almost all motorhomes, to be zero emission vehicles by 2036 and would have required fleet owners to phase in increased percentages of zero emission vehicles between now and 2035. This would have impacted RV rental companies who had fleets of 50 or more motorhomes operating in California.
However, on January 14, 2025, CARB announced that it had withdrawn its request for a waiver and authorization for the addition of the Advanced Clean Fleets regulation to its emissions control program. At this time, CARB is evaluating next steps but is not enforcing the existing portions of the Advanced Clean Fleet regulation that requires a federal waiver or authorization, such as the portions that apply to high priority and drayage fleets.
Clean Truck Check
CARB promulgated the Heavy-Duty Inspection and Maintenance program, now known as Clean Truck Check, in 2021. CARB has amended its original regulatory proposal on the program to exempt diesel motorhomes registered in states other than California, so long as they are being used for non-commercial uses. This action followed the receipt of a letter from the RV Industry Association, the National Association of RV Parks and Campgrounds (now Outdoor Hospitality Industry), and the CampCalNOW RV Park and Campground Alliance (now California Outdoor Hospitality Association).
California registered diesel motorhome owners are required to submit annual periodic emissions testing data and demonstrate compliance by submitting a passing applicable periodic test. This should not be burdensome to California motorhome owners, as it mirrors to a great degree the “smog check” they already must pass with their light-duty cars and trucks. Annual inspection is also a victory, as most diesel trucks and other vehicles besides motorhomes have to show compliance on a semi-annual basis.
Upcoming Event
On April 18, CARB will be coming to Fortuna, California, for the next stop of a multi-stop roadshow on the Clean Truck Check program throughout California. California-registered diesel motorhome owners are invited to attend. It will take place from 9 a.m. to 1 p.m. at the River Lodge Conference Center, 1800 Riverwalk Dr.
Registration is required for this event and is available here.
The event will include:
- One-on-one compliance assistance with CARB staff
- Overviews of Clean Truck Check, Off-Road Diesel and Zero-Emission Forklift programs
- Overview of Compliance Support
- Overview of Incentive Funding and Q&A
- Zero-Emission Heavy-Duty Fleets Panel Discussion: Continuous Engagement
The final agenda will be available on the registration page and will be shared prior to the event.
For more information on any of these CARB issues, please contact RV Industry Association’s Director of State Affairs Michael Ochs at mochs@rvia.org.
