Vehicle Emissions Inspection and Maintenance (I/M): Policy and Technical Guidance
On this page, guidance on:
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 policy and technical guidance that EPA has developed on several topics.
- Guidance for On-Road Testing Requirements for Enhanced Vehicle Inspection and Maintenance (I/M) Programs (pdf) (March 2020, EPA-420-B-20-020)
This document provides guidance to clarify how the on-road testing requirement can be met in states with enhanced I/M programs.
- Vehicle Emission Inspection and Maintenance (I/M) Provision in the Fixing America’s Surface Transportation (FAST) Act (December 2016) This document provides clarification regarding the obligations of states versus EPA with regard to the I/M provision of the FAST Act exempting certain replica vehicles from I/M. Please note that the Clean Air Act amendment that was made as part of the FAST Act continues to apply as described in this guidance.
- Performing On-Board Diagnostic System Checks as Part of a Vehicle Inspection and Maintenance Program (pdf) (EPA420-R-01-015, June 2001)
The guidance document 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).
- Improving I/M Performance and OBD Monitor Readiness Memo (pdf) This memorandum updates the list of vehicles in the June 2001 guidance that exhibit OBD monitor related readiness issues.
- I/M OBD Vehicles Readiness Exception List (pdf) (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.
- Guidance on Vehicle Inspection and Maintenance (I/M) Test Data Statistics as Part of Annual I/M Reporting Requirements (pdf) (May 2020, EPA-420-B-20-033)
This document provides guidance to help states and local agencies develop required annual reports for I/M programs.
- Guidance on Biennial Performance Evaluation Requirements for Enhanced Vehicle Inspection and Maintenance (I/M) Programs (pdf) (June 2020, EPA-420-B-20-040)
This document provides guidance to clarify how the biennial performance evaluation requirements can be met for states with enhanced I/M programs.
- Performance Standard Modeling for New and Existing Vehicle Inspection and Maintenance (I/M) Programs Using the MOVES Mobile Source Emissions Model (pdf) (EPA-420-B-14-006, January 2014)
This document provides clarification on how to quantify I/M emission reductions for planning purposes using the MOVES generation of mobile source emission factor models, including a discussion of I/M modeling changes since the previous mobile source emission factor model, MOBILE.
EPA notes that it is currently updating this guidance to reflect MOVES3. For additional information for modeling I/M programs in MOVES3, please see the latest technical guidance: Using MOVES to Prepare Emission Inventories for State Implementation Plans and Transportation Conformity (pdf) (November 2020, EPA-420-B-20-052).
- Guidance on the Use of Remote Sensing for Evaluation of I/M Program Performance (pdf) (EPA420-B-04-010, July 2004)
This document is intended to provide states with technical guidance on how to perform biennial I/M program evaluations using RSD technology. See EPA’s June 2020 Biennial Program Evaluation Guidance for further information about meeting this I/M requirement.