California Code, Labor Code - LAB § 7301

No conveyance shall be operated in this state unless a permit for its operation is issued by or in behalf of the division, and unless the permit remains in effect and is kept posted conspicuously on the conveyance. Operation of a conveyance without a permit or failure to post the permit conspicuously shall constitute cause for the division to prohibit use of the conveyance, unless it can be shown that a request for issuance or renewal of a permit has been made and the request has not been acted upon by the division.