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On-Board Diagnostics (OBD)

OBD and Inspection and Maintenance

This page provides regulatory and technical information on OBD and inspection and maintenance checks, including archives of past documents. The Clean Air Act requires 33 state and local areas to conduct vehicle inspection and maintenance programs to control vehicle emissions and help meet national air quality standards. A majority of these state and local areas have already incorporated the use of OBD technology into vehicle inspections, and more are planning to do so in the future.

Regulations

NOTE: You will need Adobe Acrobat Reader, available as a free download, to view some of the files on this page. See EPA's PDF page to learn more about PDF, and for a link to the free Acrobat Reader.

Final Implementation Guidance: Performing On-Board Diagnostic System Checks as Part of a Vehicle Inspection and Maintenance Program (PDF) (37 pp, 320K, EPA420-R-01-015, June 2001)
The final guidance document entitled, "Performing On-Board Diagnostic System Checks as Part of a Vehicle Inspection and Maintenance Program," contains EPA's recommendations regarding the effective implementation of OBD-I/M checks in I/M programs. The recommendations contained in this guidance are consistent with EPA's amended OBD-I/M requirements, published April 5, 2001 (66 FR 18156).

Final Rulemaking: Amendment to Vehicle Inspection Maintenance Program Requirements Incorporating the On-Board Diagnostic (PDF) (24 pp, 210K, published April 5, 2001)
The Final Rulemaking document entitled, "Amendment to Vehicle Inspection Maintenance Program Requirements Incorporating the On-Board Diagnostic Check", was signed March 28, 2001, and published in the Federal Register on April 5, 2001. It provides several options for extending the deadline for implementing OBD checks in I/M programs. The rule also revises failure and rejection criteria and provides the interim method for estimating OBD check credit under the MOBILE5 model.

Inspection Maintenance Program Requirements Incorporating the Onboard Diagnostic Check: Response to Comments (PDF) (50 pp, 80K, EPA420-R-01-003, January 2001)
Provides EPA's response to comments received on the September 20, 2000, notice of proposed rulemaking entitled, "Amendments to Vehicle Inspection Maintenance Program Requirements Incorporating the On-Board Diagnostic Check," not otherwise addressed in the final rulemaking action associated with that proposal.

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Technical Documents

Improving I/M Performance and OBD Monitor Readiness Memo (PDF) (2 pp, 31K, May 2011)
OBD Readiness Testability Issues (PDF) (7 pp, 185K, EPA-420-B-12-044, updated June 2012)
This memo and accompanying document update the I/M OBD Vehicles Readiness Exception List (EPA420-F-08-009, January 2008) to list specific vehicle makes and models with OBD readiness issues and make suggestions for how I/M programs can improve operational performance by addressing monitor readiness.

I/M OBD Vehicles Readiness Exception List (PDF) (6 pp, 190K, EPA420-F-08-009, January 2008)
This document lists vehicles that appear to be “Not Ready” for testing using the onboard diagnostic (OBD) system found on 1996 and newer vehicles.

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