Cal. Pub. Util. Code § 2119

Every passenger stage corporation and every officer, director, agent, or employee of a passenger stage corporation, who displays on any vehicle any identifying symbol other than one prescribed by the commission pursuant to Section 1038.5, or who fails to remove an identifying symbol when required by the commission, is guilty of a misdemeanor and is punishable by a fine of not more than one thousand dollars ($1,000), by imprisonment in the county jail for not more than one year, or by both.