California Code, Labor Code - LAB § 6321

No person or employer shall be given advance warning of an inspection or investigation by any authorized representative of the division unless authorized under provisions of this part.

Only the chief or, in the case of his absence, his authorized representatives shall have the authority to permit advance notice of an inspection or investigation. The director shall, as soon as practicable, set down limitations under which an employer may be granted advance notice by the chief. In no case, except an imminent danger to the health or safety of an employee or employees, is advance notice to be authorized when the investigation or inspection is to be made as a result of an employee complaint.

Any person who gives advance notice of any inspection to be conducted, without authority from the chief or his designees, is guilty of a misdemeanor and shall, upon conviction, be punished by a fine of not more than one thousand dollars ($1,000) or by imprisonment for not more than six months, or by both.