Section 554.6 - Opening an investigation(a) A compliance or defect investigation is opened either on the motion of the Administrator or his delegate or on the granting of a petition of an interested party under part 552 of this chapter.(b) A manufacturer is notified immediately by telephone of any compliance test failure in order to enable the manufacturer to begin his own investigation. Notification is sent by mail at the beginning of any defect or noncompliance investigation.