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California adopts emergency vehicle emissions regulations
2025-12-02T06:00:00Z
Effective date: October 2, 2025
This applies to: Entities subject to CARB’s vehicle emissions regulations
Description of change: Congressional resolutions disapproved the waivers for the California Air Resources Board’s (CARB’s) Advanced Clean Cars II and Heavy-Duty Vehicle and Engine Omnibus Low NOx (Omnibus) regulations.
Through an emergency rulemaking, CARB adopted the Emergency Vehicle Emissions Regulations, reinstating at a minimum earlier-adopted regulations displaced by Advanced Clean Cars II and Omnibus:
- The Low-Emission Vehicle Regulation (LEV) III regulation and associated on-board diagnostic requirements, and
- Medium- and heavy-duty regulations.
The regulation applies until litigation is resolved.
Regulated entities may follow either:
- The LEV IV (part of Advanced Clean Cars II) or Omnibus standards, or
- The LEV III and pre-Omnibus standards.
View related state info: Air programs — California Air Resources Board (CARB)




















































