SAE J1939-03 provides requirements and guidelines for the implementation of On Board Diagnostics (OBD) on heavy-duty vehicles (HDV) using the SAE J1939 family of standards. The guidelines identify where the necessary information to meet OBD regulations may be found among the SAE J1939 document set. Key requirements are identified here to insure the interoperability of OBD scan tools across individual OBD compliant vehicles.