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CARB proposes amendments to the Heavy-Duty Engine and Vehicle Omnibus Regulation

3 August 2023

The California Air Resources Board (CARB) has proposed amendments to the Heavy-Duty Engine and Vehicle Omnibus regulation that would provide additional flexibility for manufacturers of model year (MY) 2024-2026 heavy-duty engines. The proposal follows the recent agreement on future emission regulations between CARB and engine manufacturers.

The California Omnibus regulation established more stringent NOx and PM standards applicable to new 2024 and subsequent MY medium- and heavy-duty diesel and Otto-cycle engines. As 2024 model year certification approached, CARB said it became aware that “while the technology for diesel-fueled Omnibus compliant engines was available, manufacturers did not intend to produce such engines for some categories of trucks in California.” Therefore, CARB staff is proposing to amend the legacy engine provisions in the Omnibus regulation to provide additional compliance flexibility to allow manufacturers to produce and certify greater numbers of 2024 through 2026 MY legacy engines.

The Omnibus regulation currently contains a provision that allows manufacturers to produce a fraction of their 2024 and 2025 MY heavy-duty diesel engines (HDDE) below 525 bhp certified to the current 0.20 g/bhp-hr NOx standard—referred to as ‘legacy engines’—provided they offset any resulting legacy engine NOx or PM emission deficits with emission credits.

CARB is proposing two flexibility options for manufacturers:

A public hearing on the proposal has not been scheduled. CARB will conduct a public hearing only if one is requested. Any interested person may request a public hearing by September 3, 2023.

Source: CARB