Proposed CARB Regulation Threatens Availability Of Diesel Engines

Jul 19, 2021

Provisions of a proposed California Air Resource Board (CARB) rule will greatly increase the cost of manufacturing diesel engines beginning in 2024. Uncertainty over various elements of the rule is causing many engine manufacturers to question whether they will even produce these engines, especially in the sizes most utilized in motorhome chassis, which are in the 340-525 horsepower range.

Specifically, the CARB Omnibus Low NOx rule, which goes into effect in 2024, requires the manufacturers of heavy-duty diesel engines to comply with vastly more stringent exhaust emission standards, amends in-use test procedures, creates modifications to the durability demonstration, lengthens warranty and useful life periods, and increases emissions date collection and reporting.

While regulations set by CARB apply only to vehicles sold in California, the regulations become de facto nationwide regulations as companies do not build different engines for only California, but rather build engines to meet the most stringent state requirements, allowing their engines to be sold in all states. Additionally, 13 other states have policies of mirroring CARB regulations.

With these proposed regulations threatening to impact the availability of diesel engines for RVs, the RV Industry Association is working with engine manufacturers such as Cummins and other stakeholders to find a solution. In furthering that goal, this month, the Association submitted comments asking for an exemption from the requirements for model year 2024 and 2025 engines and the opportunity for RV Industry Association member companies to meet with CARB. Read the full comments here.

For more information on this issue, contact RV Industry Association Director of Government Affairs Mike Ochs at