your dash isnt properly secured to the vehicle.....
CA VC:
5200. (a) When two license plates are issued by the department for use upon a vehicle, they shall be attached to the vehicle for which they were issued, one in the front and the other in the rear.
5201. License plates shall at all times be securely fastened to the vehicle for which they are issued so as to prevent the plates from swinging, shall be mounted in a position so as to be clearly visible, and shall be maintained in a condition so as to be clearly legible. The rear license plate shall be mounted not less than 12 inches nor more than 60 inches from the ground, and the front license plate shall be mounted not more than 60 inches from the ground
