Smog Check Program

This page last reviewed February 22, 2010


The Smog Check Program is administered by the Bureau of Automotive Repair (BAR), which is a part of the California Department of Consumer Affairs.  The Air Resources Board (ARB), by contrast, is a part of the California Environmental Protection Agency.

For information about your vehicle and the Smog Check Program, please visit the BAR website, or contact them toll-free at (800) 952-5210. 


Smog Check Program Evaluation   new

The final report is now available for a study evaluating the Smog Check Program based on data collected from random in-use vehicles.

  • Evaluation of the California Smog Check Program Using Random Roadside Data, March 12, 2009 ( PDF)
  • Addendum to the Report, February 2010 ( PDF)

OBD-Only Based Smog Check Inspections  

ARB staff has released a report evaluating the benefits and challenges of eliminating tailpipe testing as part of the Smog Check inspection procedure for all or most vehicles equipped with On-Board Diagnostic II (OBD II) Systems.

Transitioning Away from Smog Check Tailpipe Emission Testing in California for OBD II Equipped Vehicles, March 2009( PDF)

Remote Sensing Pilot Study  

The reports for the study initiated by ARB and BAR have been finalized and are available below.

Evaluation of Remote Sensing for Improving California's Smog Check Program, March 3, 2008 (Final Report)  (PDF)

Review of Literature on Remote Sensing Devices, August 26, 2004 (Paper Study) (PDF)

Estimating Benefits of Improvement Strategies (including RSD) for the California I/M Program:

An Inspection and Emissions Forecasting System, March 1, 2008 (Modeling Report)  (PDF)

Estimating Benefits and Costs of Improvement Strategies for the California I/M Program:

Implementation Options for Using RSD, March 2, 2008 (Implementation Report)  (PDF)

Use of California Remote Sensing Pilot Project Data for On-road Fleet and Emissions Characterization,
and Evaluation of the Enhanced Smog Check Program , October 2005 (PDF) 

Response to Peer Review Comments, March 7, 2008   (PDF)



Smog Check Documents

Environmental Impacts of Implementing a Low Pressure Evaporative Test in the California Smog Check Program (PDF)

Control Concept Evaluation - Four-Wheel Dynamometer Requirements As Part of Smog Check South Coast Air Basin (PDF)



2004 Smog Check Program Evaluation

ARB and BAR have finalized a report to the Legislature and the Inspection and Maintenance Review Committee (IMRC), Evaluation of the California Enhanced Vehicle Inspection and Maintenance (Smog Check) Program (April 2004), as required under State law.  The transmittal letter to the IMRC is also available for review.

Final Report   (PDF)

Transmittal Letter to the IMRC   (PDF)

The methodologies and calculations used to estimate the emissions benefits in the Evaluation of the California Enhanced Vehicle Inspection and Maintenance (Smog Check) Program (April 2004) are explained in a technical support document.  The transmittal letter to the IMRC is also available for review.

Cover Page and Introductory Comments   (PDF)

Part 1 -- Analyses Conducted by ARB Staff   (PDF)

Part 2 -- Further Analyses Conducted by Sierra Research   (PDF)

Transmittal Letter to the IMRC   (PDF)



2000 Report on Smog Check

ARB, in consultation with BAR, finalized a report on the effectiveness of Smog Check entitled Evaluation of California's Enhanced Vehicle Inspection and Maintenance Program (Smog Check II).  

To find out more about ARB's other programs to control emissions from motor vehicles , please visit ARB's Mobile Sources Program Portal.


Program Contact
If you have any questions regarding the air quality elements of the Smog Check Program, please contact:

Tom Scheffelin
Transportation Analysis Section
Planning and Technical Support Division
Air Resources Board
P.O. Box 2815
Sacramento, CA 95812
(916) 327-7847

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