CARB Quietly Enforces Diesel TRU Rules After Years of Inaction

Key Details California Air Resources Board (CARB) has begun enforcing diesel transport refrigerated unit (TRU) regulations without formal announcement, according to a law firm alert to clients. The rules themselves date back to 2022 with no recent changes, but enforcement appears to be ramping up now after years of minimal activity. Why It Matters TRU owners and large warehouses receiving refrigerated shipments must now comply with registration, reporting, and operational requirements. This applies to TRU operators both inside and outside California, making compliance a critical issue for any carrier moving temperature-controlled goods to the state. What's Driving This With California's Advanced Clean Trucks and Advanced Clean Fleets regulations sidelined due to federal conflicts, CARB appears to be shifting focus to the existing TRU framework. Enforcement attorney Brian Cullen notes the rules "have been on the books but not really been enforced," suggesting the agency is leveraging available regulatory tools while broader clean truck goals remain stalled. Next Steps Drivers and fleet operators should review current TRU registration status and ensure warehouse partners maintain proper disclosure documentation. Non-compliance could result in penalties as CARB actively pursues this previously dormant regulation.