California Truck Idling Law
California has the strictest rule in the west. No diesel truck over 10,000 pounds may idle its main engine more than 5 minutes anywhere (13 CCR 2485, CARB). 2008-and-newer engines must EITHER shut down automatically at 5 minutes OR carry a "Certified Clean Idle" label; only labeled trucks may idle beyond 5 minutes, and even then not within 100 feet of homes, schools, hotels, hospitals, or care facilities. The old sleeper-berth idling exemption expired January 1, 2008 for all trucks regardless of engine year, so a plain pre-2008 engine gets no berth idling break — plan on a Clean Idle engine or an APU. Fines start at $300, and the DMV can block your registration until you clear them.
When you can keep idling
- Traffic or queuing, kept at least 100 feet from any restricted area
- Repairs, service, or DPF regeneration
- PTO and reefer work
- A safety or health emergency
- Certified Clean Idle engines (2008+, optional NOx idling standard) may idle beyond 5 minutes, except within 100 feet of a restricted area
APUs and idle-reduction gear
A diesel auxiliary power system cannot run over 5 minutes within 100 feet of a restricted area (homes, schools, hotels, hospitals, senior or child care facilities), and 2007-and-newer trucks need PM controls. California grants NO weight allowance for APUs or idle-reduction gear — an APU-equipped truck still scales at the normal 80,000-pound limit.
City and county ordinances
- Regional air districts (South Coast, San Joaquin Valley, Bay Area) mirror the 5-minute rule.
California Idling Law FAQ
Is there a truck idling law in California?
How long can a truck idle in California?
What is the fine for idling in California?
Does an APU count as idling in California?
Reference information for planning, not legal advice. Traffic laws change and this can be out of date, so always confirm the current statute and obey posted signs before you rely on it. Last reviewed July 2026. Source: https://afdc.energy.gov/fuels/laws/IR?state=CA. See our Terms & Disclaimer.
More for California
Check California before you roll
Live weather, closures, and hazards on one map. Free, no account.
Open Live Map →