An official website of the United States government.

We've made some changes to EPA.gov. If the information you are looking for is not here, you may be able to find it on the EPA Web Archive or the January 19, 2017 Web Snapshot.

Vehicle Emissions On-Board Diagnostics (OBD)

You will need Free Viewers and Adobe Reader to view some of the files on this page. See EPA’s About PDF page to learn more.

On this page:

Vehicle Service Information

This section provides valuable regulatory and technical information for the automotive industry, including archives of past documents.

2003 Final Rule

Proposed Amendments to 1995 Final Rule

1995 Final Rule

Technical Documents

On-Board Diagnostic Hand-Held Scan Tool Technology: Adherence to the Society of Automotive Engineers Requirements for Scan Tools and an Evaluation of Overall Scan Tool Capability (PDF) (27 pp, 69 K, EPA420-R-00-017, October 2000)

Top of Page

OBD and Inspection and Maintenance

This section 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.

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).

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, 80 K, 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.

Top of Page


Technical Documents

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.

This document lists vehicles that appear to be “Not Ready” for testing using the onboard diagnostic (OBD) system found on 1996 and newer vehicles.

State Agencies

On-Board Diagnostics (OBD) offers significant benefits to state and local agencies working to improve air quality through vehicle inspection and maintenance programs. By providing technicians with timely and accurate emissions data and helping vehicle owners better maintain their vehicles, OBD plays a key role in helping states meet national air quality standards.

Whether your state has already implemented OBD checks or is planning to do so in the near future, this Web site will provide you with a wealth of information, including:

Related Links:

Equipment and Tool Institute
Learn more about Controlled Area Network (CAN) equipped vehicles.

OBD Clearinghouse: Weber State University's Center for Automotive Science and Technology
Learn the latest on state and local OBD implementation, technician training opportunities and state outreach materials.

Top of Page