Vehicle Emissions Inspection and Maintenance (I/M): General Information and Regulations
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Vehicle inspection and maintenance (I/M) programs help improve air quality by identifying cars and trucks with high emissions and that may need repairs. Owners or operators of vehicles with high emissions are notified to make any repairs so that emissions are within legal limits. The 1990 Amendments to the Clean Air Act (CAA) established I/M requirements for several areas across the country. This page contains general information on I/M, the current I/M regulations, and the chronological list of rulemakings promulgated by EPA to facilitate state implementation of this CAA requirement.
General Information on I/M
- Overview of Vehicle Inspection and Maintenance (I/M) Programs (pdf) (157 KB, October 2021, EPA-420-F-21-067)
This document provides information on I/M programs such as where I/M programs are required and an overview of I/M testing.
Current I/M Regulations
The current I/M regulations may be found at 40 CFR part 51, Subpart S.
Chronological List of I/M Rulemakings
Amendment to Align I/M Program and Attainment SIP Due Dates
- In 2015, the I/M regulations were amended as part of the Implementation of the 2008 National Ambient Air Quality Standards for Ozone: State Implementation Plan Requirements rulemaking. In this final rule, EPA aligned the due date for the I/M program state implementation plans (SIP) with the due date of the attainment demonstration SIP.
- Final Rule 2015 (pdf) (498 KB, published March 6, 2015)
- Proposed Rule 2013 (pdf) (178 KB, published June 11, 2013)
Amendments to Vehicle Inspection Maintenance Program Requirements to Address the 8-Hour National Ambient Air Quality Standard for Ozone
- Final Rule 2006 (pdf) (177 KB, published April 7, 2006)
- Fact Sheet 2006 (pdf) (148 KB, EPA420-F-06-028, March 2006)
- Proposed Rule 2005 (pdf) (180 KB, published January 6, 2005)
- Fact Sheet 2004 (pdf) (26.8 KB, EPA420-F-04-059, December 2004)
Amendments to Vehicle Inspection Maintenance Program Requirements Incorporating the Onboard Diagnostic Check
- Final Rule 2001 (pdf) (235 KB, published April 5, 2001)
- Proposed Rule 2000 (pdf) (262 KB, published September 20, 2000)
Additional Flexibility Amendments to Vehicle Inspection Maintenance Program Requirements; Amendment to Final Rule
- Final Rule 2000 (pdf) (265 KB, published July 24, 2000)
- Proposed Rule 1999 (pdf) (218 KB, published August 20, 1999)
I/M Program Requirement - On-Board Diagnostic Checks Amendment to the Final Rule
- Final Rule 1998 (pdf) (140 KB, published May 4, 1998)
- Final Rule Fact Sheet 1998 (pdf) (18.9 KB, EPA420-F-98-017, April 1998)
- Proposed Rule Fact Sheet 1998 (pdf) (18.0 KB, EPA420-F-98-002, January 1998)
- Proposed Rule 1997 (pdf) (121 KB, published December 22, 1997)
Minor Amendments to Inspection Maintenance Program Evaluation Requirements; Amendment to the Final Rule
- Final Rule 1998 (pdf) (144 KB, published January 9, 1998)
- Proposed Rule 1997 (pdf) (133 KB, published September 19, 1997)
Minor Amendments to Inspection/Maintenance Program Requirements/M Program Requirements Minor Amendments
- Direct Final Rule 1996 (pdf) (122 KB, published September 23, 1996)
I/M Program Requirement for On-Board Diagnostic Checks
- Correction of Final Rule 1996 (pdf) (101 KB, published August 27, 1996)
- Final Rule 1996 (pdf) (160 KB, published August 6, 1996)
- Proposed Rule 8/1995 (pdf) (153 KB, published August 18, 1995)
Inspection/Maintenance Flexibility Amendments (Ozone Transport Region)
- Final Rule 7/1996 (pdf) (134 KB, published July 25, 1996)
- Proposed Rule 10/1995 (pdf) (162 KB, published October 23, 1995)
Inspection/Maintenance / Flexibility Amendments
- Final Rule 9/1995 (pdf) (162 KB, published September 18, 1995)
- Proposed Rule 4/1995 (pdf) (156 KB, published April 28, 1995)
Inspection/Maintenance Program Requirements -- Provisions for Redesignation
- Final Rule 1995 (pdf) (127 KB, published January 5, 1995)
- Proposed Rule 1994 (published June 28, 1994)
Inspection/Maintenance Program Requirements
- Final Rule 1992(pdf) (268 MB, published November 5, 1992)
- Proposed Rule 1992 (pdf)(224 MB, published July 13, 1992)