I/M Lookup Table Software

A Comprehensive Lookup Table of Vehicle Emissions and OBDII Test Parameters for Model Years 1973-2009 (Copyright © 2009 by Sierra Research, Inc. All Rights Reserved.)

Under contract to the U.S. Environmental Protection Agency (U.S. EPA), Sierra Research developed both the original I/M Lookup Table and annual updates to the table until U.S. EPA discontinued funding publicly available updates in 2000.  Version 1.8.5 of the I/M Lookup Table, the last publicly available version developed with U.S. EPA funding that was released in October 2000, includes loaded mode tailpipe and gas cap testing data for model year (MY) 1973-1999 passenger cars and light-duty trucks.  Since the development of Version 1.8.5, Sierra has developed and licensed the use of two separate, proprietary updated lookup tables.  The first includes information for performing loaded mode tailpipe tests and gas cap tests on MY1973-2009 vehicles, and the other information for performing On-Board Diagnostic (OBDII) tests on MY1996-2009 vehicles.  These are collectively referred to as the Sierra Research I/M Lookup Table.  (No OBDII test information was included in the U.S. EPA funded updates.)

The Sierra Research I/M Lookup Table is the only available lookup table of vehicle emissions and OBDII test parameters for the full range of model year 1973 and newer in-use motor vehicles.  Most United States vehicle emissions inspection and maintenance (I/M) programs use it to ensure consistent and proper testing of motorists' vehicles.  I/M programs are using the contents of the lookup table to:

  • Ensure that all 2WD vehicles are properly loaded during transient (e.g., IM240, IM147, IM93, BAR31 or MA31, etc.) or steady state Acceleration Simulation Mode (ASM) dynamometer testing.  This includes 1996+ models, to assure proper backup tailpipe testing or for program evaluation purposes.  (Some states also plan on tailpipe retests of aging OBDII vehicles to address the problem of overly frequent Malfunction Indicator Light [MIL] illumination.)
  • Provide inspectors with proper gas cap adapter information.
  • Assure that vehicle makes, models, and other identification information are consistently recorded within a program and across multiple programs (the latter is very useful for program evaluation purposes).
  • Exclude Controller Area Network (CAN) equipped vehicles from the OBDII test until CAN capable scan tools are installed in a program’s test systems.
  • Properly exclude OBDII vehicles with readiness problems from OBDII test readiness requirements.
  • Identify suspected OBDII test fraud.  The communication protocol and supported monitors (as well as other OBDII test parameters) can be used to identify suspected fraudulent OBDII testing.  This can be done through the comparison of recorded OBDII parameter values (e.g., communication protocol and supported monitors) to those contained in a "truth table" such as the Sierra Research I/M Lookup Table.

The 2009 Sierra Research I/M Lookup Table includes vehicle records for MY1973-2009 passenger cars and light-duty trucks certified by U.S. EPA as well as 8,500-10,000-lb gross vehicle weight rating (GVWR) gasoline-fueled vehicles certified in recent years.  It consists of two separate lookup tables (these can be provided as a single combined lookup table if requested by a purchaser) as described below.

Much of the data contained in this lookup table are based on motor vehicle certification and fuel economy data obtained from U.S. EPA (who in turn received the data from the individual motor vehicle manufacturers).  This includes individual vehicle records containing the following information. Note that the availability of certain vehicle parameters is limited due to its non-availability from the manufacturers or other sources.

  • Vehicle description information (model year, make, model, body style, number of cylinders, engine displacement, transmission type, fuel type, sales class, vehicle record ID number, identification of a heavy-duty vehicle [HDV] sales class that includes vehicles with a GVWR of between 8,500 lbs and 10,000 lbs [these are considered medium duty vehicles in California]).
  • Vehicle test weight information (equivalent test weight, inertia weight class, and average drive axle weight).
  • Evaporative system information (evaporative system type, and number and location of evap canisters). This is provided for only a limited number of vehicle records.
  • Horsepower and tire/roll loss settings for transient, ASM5015 and ASM2525 loaded mode exhaust emissions tests on 8.65" and 20.0" dynamometer rolls, tire/roll loss settings for testing vehicles in all-wheel drive mode.
  • Vehicle Identification Number (VIN) digit and characters to identify light trucks below 6,000 lbs GVWR, and between 6,001 and 8,500 lbs GVWR, VIN characters to identify HDVs in the following separate weight ranges when possible:
    • 8,501-9,000 lbs GVWR
    • 9,001-10,000 lbs GVWR

    These ranges were chosen to match those included in various state I/M programs. They will be provided for all applicable vehicles where available (some manufacturers do not provide a 8,500-lb GVWR breakpoint as part of their VIN codings).

  • Wheelbase (this information is provided for only a limited number of vehicle records).
  • Two-wheel drive testability parameters (drive layouts; full-time 4-wheel drive status and location of 4-wheel drive selector; traction control status, disablement status and switch location; anti-lock braking status and disablement status; and overall 2-wheel drive dynamometer test status).
  • Evaporative test parameters (main fuel tank size; auxiliary fuel tank status and size; U.S. EPA pressure test status, comments, and minimum and maximum pressures; inlet pressure test status, comments, and minimum and maximum pressures; EPA purge test status and comments; tracer purge test status, comments, and minimum and maximum pressures; and gas cap adapter information; separate Waekon and Stant gas cap adapter information). Much of this information is provided for only a limited number of vehicle records.
  • New with the 2009 update, vehicle records for MY2006 and 2009 light-duty vehicles (cars and trucks) have been added to those contained in the 2005 version of the I/M Lookup Table. This includes the MY2000-2005 records contained in the proprietary lookup tables previously developed by Sierra Research plus MY2006 and 2009 data obtained from U.S. EPA. A limited number of MY2009 records are not included since the vehicle manufacturers have not yet submitted data on all 2009 models to U.S. EPA.
  • Updates to MY2005 records that were not available in the last update have been added.
  • Corrections to pre-MY2005 records have been incorporated to address anomalies identified by Sierra Research and table users.
  • Hybrid vehicle records are included and specifically identified to allow them to be recognized automatically and subjected to special test procedures by the inspection software.
  • Records for HDVs with GVWRs of 8,501-10,000 lbs have been added. An attempt has been made to add these records for all model years (1973-2009) contained in the 2009 update; however, some records may be missing due to a lack of available data sources needed to populate the I/M Lookup Table.

Data contained in this lookup table are based on OBDII test parameter information obtained from individual motor vehicle manufacturers and other sources.  The lookup table includes individual vehicle records for 1996 and newer model years that contain the following information.  Note that certain vehicle parameters have not been populated in the table due to their non-availability from existing sources of information.

  • Vehicle description information (including vehicle record ID number) that is identical to that contained in the 2009 Enhanced I/M Lookup Table, thus allowing easy cross-referencing of the two tables.  This includes new with the 2009 update the MY2006 and 2009 vehicle records described under Item 9 above for the 2009 Enhanced I/M Lookup Table.
  • As noted above, hybrid vehicle records are included and specifically identified to allow them to be recognized automatically and subjected to special test procedures by the inspection software.
  • Overall and individual OBDII readiness monitor status: N = no known readiness issues, Y = known readiness issues based on EPA OBD-I/M Guidance (including the updated draft version of Appendix D) that require exclusion from readiness requirements (individual monitor data indicate the affected monitors).
  • Keyless ignition status: N = vehicle does not have keyless ignition, M=keyless ignition is possible/was an option from the factory, Y=vehicle has keyless ignition.
  • OBDII communication protocol: V = VPW, P = PWM, I = ISO, K = Keyword, C = CAN.
  • OBDII data link connector (DLC) location information: Location code, matching the 1-9 (or blank) U.S. EPA dashboard location map designations; open or covered; and comment field.
  • Excluded/supported readiness monitors: Y = monitor is supported, N = monitor is not supported.
  • Additional fields that have been added but not populated in the 2009 update include:
    • PID Count
    • PCM Module ID
    • Calibration Identification Number
    • Calibration Verification Number

These fields have not been populated due to the current lack of available information.  They are included as placeholders for this information, which can be added as part of future updates.  Purchasers of a license to use the 2009 update will not be provided with this information, but will instead need to purchase the license to a future update that contains the information.  Sierra Research intends to assemble information on these parameters in the future if states and I/M contractors that are collecting OBDII test information provide the applicable data for analysis.  The test data would be analyzed to determine observed and valid OBDII parameter values, which would then be added to the Sierra Research I/M Lookup Table for use as a truth table against which actual test values can be compared.

As a supplement to the base Sierra Research OBDII I/M Lookup Table, interested parties can also purchase an add-on feature that contains the following information:

  • A Sierra Research DLC Location Library of graphic images (in JPEG format) for most model year 1996 through 2005 vehicle records; and
  • The base lookup table includes an additional DLC Image field containing the filename of the corresponding DLC location graphic image for those vehicle records that have such images.

Purchasers can use the above information to access the applicable graphic DLC location image during an OBDII inspection, following the entry of the vehicle identification information needed to access the proper lookup table vehicle record.  As of January 1, 2006, the Sierra DLC Location Library includes the following:

  • JPEG files for 76% of MY1996-2005 records contained in the base OBDII lookup table that show the specific DLC location for each vehicle based on digital photographs obtained from the Weber State University Center for Automotive Science and Technology's National OBD Clearinghouse.
  • JPEG files for 18% of MY1996-2005 records that show a digital image of the generic DLC location based on the applicable U.S. EPA dashboard location map designation.  These files are provided for those records for which no specific JPEG image is available from Weber State but for which the generic U.S. EPA location information is available.
  • No image of either type is available for 6% of the MY1996-2005 records.

The percentages provided above are based on the percent of lookup table records rather than the percent of in-use vehicles covered by the specific and/or generic JPEG images contained in the Sierra DLC Location Library.  Because the available images include higher sales volume vehicles, the percentage of in-use vehicles covered by these images would be considerably higher than the indicated percentages.  It is estimated that the Sierra DLC Location Library contains specific and/or generic JPEG images for over 98% of all MY1996-2005 vehicles on a sales-weighted basis.

Sierra is not aware of any plans to fund updates to the DLC location library.

Sierra Research will provide each purchaser of a license to use the 2009 Sierra Research I/M Lookup Table with a perpetual, non-transferable license and an electronic copy of the lookup table.  Under this license agreement, the purchaser will be free to use this information as needed for a single I/M program, including distributing copies to the applicable I/M contractor, equipment manufacturers (EMs) and/or vehicle information database (VID) contractor.  All purchasers, I/M contractors, EMs and VID contractors are restricted from using or distributing the information for non-program purposes outside of a single specific program.

Purchasers must attest and agree by signing the order form that they will comply with all license terms and conditions as listed on the order form.

Contractors responsible for obtaining individual update licenses for multiple I/M programs will be charged the same price for each program.  Individual I/M Lookup Table licenses are valid only for single programs and purchasers are prohibited from using a single licensed copy of the update in multiple programs.  Sierra will be the sole judge of what constitutes a "single" program.

The purchase cost of a license to use the 2009 Sierra Research I/M Lookup Table is $15,000.  Purchasers can order the 2009 update by accessing and completing the order form available through the Sierra Research website, and mailing or faxing the completed form to the address/telephone number shown on the form.

If requested, the 2009 Sierra Research will provide the I/M Lookup Table in the specific electronic format of the vehicle lookup table used in the purchaser's I/M program.  Up to 10 hours of telephone assistance will also be provided to each purchaser in understanding and utilizing the updated table, regardless of whether a program-specific vehicle lookup table is provided.  Both the development of a program-specific lookup table and the 10 hours of telephone assistance are standard support items included as part of the $15,000 purchase price.