Cal. Veh. Code § 14253

Unless probation was imposed for a cause which is continuing, the probationer, after not less than one year, may request in writing the termination of the probation and the return of his regular license. Upon a showing that there has been no violation of the terms or conditions of the probation for a period of one year immediately preceding the request, the department shall terminate the probation and either restore to the person his driver’s license or require an application for a new license.