Final Technical Support Document for "Amendments to Vehicle Inspection Maintenance Program Requirements Incorporating the Onboard Diagnostic Check"

On September 20, 2000, the Environmental Protection Agency (EPA) proposed to revise existing Motor Vehicle Inspection/Maintenance (I/M) requirements related to the incorporation of Onboard Diagnostic (OBD) checks into such programs. Among other things, the proposed regulatory revisions -- once adopted -- will accomplish the following: 1) Allow the OBD-I/M check to replace tailpipe and evaporative system testing on OBD-equipped vehicles (with the exception of the gas cap evaporative system test); and 2) Revise the failure and rejection criteria for the OBD-I/M check. This Technical Support Document (TSD) provides EPA’s technical justification for these amendments, based upon the Agency’s findings gathered during three separate OBD-I/M pilot studies. These three pilot studies focused on the following aspects of OBD-I/M testing: 1) OBD-I/M’s effectiveness as compared to existing exhaust emission testing; 2) OBD-I/M’s effectiveness in identifying faults in the evaporative system; and 3) the unique implementation issues associated with incorporating checks of the OBD system into a traditional I/M setting. The results of EPA’s pilot testing were shared while still in progress with members of the OBD workgroup of the Mobile Source Technical Review Subcommittee established under the Federal Advisory Committee Act (FACA). The OBD workgroup’s membership includes representatives from the testing and repair industries, vehicle manufacturers, the states, EPA, scan tool manufacturers, the academic community, private consultants, and providers of OBD technician training. Feedback from the workgroup was used to help guide the progress of the pilots, to interpret the results along the way, and to develop the proposed amendments to the rule’s existing OBD-I/M requirements.


  • English

Media Info

  • Media Type: Digital/other
  • Features: Appendices; References; Tables;
  • Pagination: 49p

Subject/Index Terms

Filing Info

  • Accession Number: 01535738
  • Record Type: Publication
  • Report/Paper Numbers: EPA420-R-01-002
  • Files: TRIS
  • Created Date: Aug 27 2014 10:50AM