CARB does not have in-person consultations about diesel truck regulations.

Due to the high call volume we are experiencing on our diesel hotline, CARB cannot provide in-person consultations about diesel truck regulations. If you need assistance with diesel rule compliance or reporting, please contact us by phone or email. Walk-in visitors will be turned away.

For the quickest assistance with your diesel compliance or reporting inquiries, please call the Diesel Hotline at 866-6DIESEL (866-634-3735). Agents are available by phone from 8 AM to 5 PM weekdays. During high call volume periods, there may be longer wait times. Ideal times to call are from 8 AM to 9:30 AM and 1 PM to 2:30 PM.

If you would like to submit compliance or reporting documentation, please email scanned copies to or mail your copies to:

California Air Resources Board
Attn: Diesel Hotline Staff
P.O. Box 2815
Sacramento, CA 95812