Technical Highlights

IM OBD Vehicles Readiness 

Exception List 

Introduction 

In June 2001, EPA issued guidance on “Performing Onboard System 

Diagnostic Checks as Part of a Vehicle Inspection and Maintenance Program” that 

includes an Appendix D, entitled “Manufacturers Known to Have Readiness Issues.” 

This appendix lists vehicles that appear to be “Not Ready” for testing using the 

onboard diagnostic (OBD) system found on 1996 and newer vehicles. It was agreed 

upon by EPA and the OBD stakeholder community that at a minimum Appendix D 

should be updated to include more recent model year vehicles, as well as provide any 

new information such as Technical Service Bulletins or Recalls that may be available 

to address readiness issues for specific vehicles. 

The first step in this effort was to analyze field data from state programs 

to identify those vehicles that were exhibiting readiness problems during their 

scheduled OBD test. EPA performed an analysis on over nine million initial test 

records from calendar year 2005 covering model years 1996 through 2004 and in 

April 2007 issued a report (EPA420-F-07-025) containing the results of this analysis. 

The salient points are highlighted below. 

Several factors were used to analyze the data in the April 2007 report: make, 

model, model year, the fraction of vehicles in a make or model that were Not Ready, 

and the total number of records for that make or model. The model designations 

contained in the data provided by the states were used as received. Some of the 

model designations vary among the five states analyzed and even within a state 

some designations seem to be repetitive (e.g., the 2- and 4-wheel drive versions of 

a vehicle are entered as different models), thus expanding the number of “models” 

in the dataset. A range of criteria was used to investigate the magnitude of the Not 

Ready problem. Using 8% Not Ready, a minimum of 50 vehicles tested, and state 

model definitions, many more models with readiness problems were identified than 

had been originally identified in an informal stakeholder survey. The EPA analysis 

also shows that the number and percentage of vehicles by model year with Not 

 Some of the model duplication is also due to the VIN decoder used to identify models in the MO and 

NC data as those programs did not report vehicle model in CY05. 

Office of Transportation and Air Quality 

EPA420-F-08-009 

January 2008 
Technical Highlights

Ready issues has declined significantly since OBD systems were first installed in 1996.The 

overwhelming majority of makes have readiness issues in less than 7% of its vehicles. 

The April 2007 analysis did not attempt to investigate the causes for the Not Ready 

issues. Such causes include: design problems with the vehicle’s OBD system, scan tool/ 

inspection software problems, vehicles being tested that are not OBD equipped, and vehicles 

that have already been identified as having readiness issues and have a solution identified. EPA 

has established a workgroup to look into potential readiness problems based on the analysis 

discussed in this report. 

It was originally intended that the workgroup would focus on those models that have 

a Not Ready rate of 30% or more; however, a number of vehicles in this category were found 

to be over 8500 lbs. GVWR, already in the existing Appendix D, or subject to a specific recall 

campaign. Therefore, this update will provide a listing of these vehicles, and the next update 

will focus on those vehicles with Not Ready rates greater than 30% that are being investigated 

further. The next update will address vehicles with Not Ready rates greater than 20% also. 

It should be noted that the analyses done for this document included data from GA and 

WI, so that the total number of test records was increased to approximately 12 million. 

Solutions for those vehicles under evaluation will be developed by the stakeholder 

workgroup and shared through periodic updates to the broader IM community via mechanisms 

such as the IM Solutions List Server. 

Please contact Gene Tierney (tierney.gene@epa.gov) or Lee Cook (cook.leila@epa.gov) 

for questions regarding this document. 

Over 30% Not Ready:Vehicles Between 8,500 & 14,000 lbs. GVWR 

The table below provides a summary of the Makes, Models, and Model Years of vehicles 

that were found to be judged Not Ready from the analysis of the seven-state data; however, they 

are also over 8500 lbs. GVWR and, therefore, are not required to be federally OBD-compliant 

until a 40% phase-in beginning with the 2004 model year for gasoline and a 50% phase-in 

beginning with the 2005 model year for diesel. For this reason OTAQ does not recommend 

these vehicles be OBD-tested. If a state does decide to OBD test these vehicles, the OBD system 

information should not be the sole source of information for any pass/fail decision. Furthermore, 

any state that decides to OBD-test these vehicles should exercise caution even if the testing is 

done on an advisory basis. 

It was recognized that those vehicles appearing in Table 1 were identified by chance and, 

therefore, less than a complete list. A second table was created to address this issue and is much 

more extensive. It lists all vehicles over 8500 lbs. GVWR certified from MY00 through MY07 

and includes engine size. Due to its size, it is only available electronically on the OTAQ web 

page. (See File Table 1a.) 

IM OBD Vechicles Readiness Exception List 
Table 1: Vehicles Over 8500 lb. GVWR Identified in Data with >30% Not Ready 

Technical Highlights

MY

Make Model 1996 1997 1998 1999 2000 2001 2002 2003 2004

Chevy

Chevy

Chevy

Chevy

Chevy

Chevy

Chevy

Chevy

C2500 x x x x

G1500 x x

G2500 x x x x x x

G35 x

K2500 x x

K3500 x

Savanna x x

3500 x

Dodge

Dodge

Dodge

Dodge

Dodge

Dodge

B2500 x x x x

B3500 x x

Ram 2500 x x x

Ram 3500 x x x

Ram Van x x x x x x x

Ram Wagon x x x

Ford

Ford

Ford

Ford

Ford

Ford

E250 x x x x x x x x x

E350 x x x x x x x

Excursion x x x

F250 x x x x x x x x

F350 x x x x

E150 x

GMC

GMC

GMC

GMC

GMC

GMC

GMC

C2500 x x x x

G25 x

G2500 x x x

G35 x

Savanna x x x x

Sierra x

3500 x

 In all tables, an “x” indicates that particular Make, Model, and MY displayed a Not Ready rate >30% in the data 

set. If the cell is blank, then that Make, Model , and MY Not Ready rate was below 30% and not the focus of this 

update even though those cells still represent vehicles that are above 8500 lb GVWR. 

IM OBD Vechicles Readiness Exception List 
Over 30% Not Ready:Vehicles Subject to Recall Campaign 

#678 TSB 18-005-01 

The following vehicles in Table 2 have been the focus of a manufacturer recall campaign 

(Recall Campaign #678). The readiness issue with these vehicles is an improper design that 

causes all monitors to set to “Not Ready” following every ignition key-off event. 

TSB 18-005-01 applies to non-California vehicles and will be performed at no cost, 

even if the warranty has expired. A similar agreement between ARB and Chrysler has been 

established for CA vehicles. 

Table 2: Recall Campaign #678 Vehicles 

MY

Make Model 1996

Chrysler Cirrus x

Chrysler Concorde x

Chrysler Intrepid x

Chrysler LHS x

Chrysler New Yorker x

Chrysler Sebring x

Dodge Avenger x

Dodge Intrepid x

Dodge Neon x

Dodge Stratus x

Jeep Eagle Talon x

Jeep Eagle Vision x

Plymouth Breeze x

Plymouth Neon x

Plymouth Voyager x

Technical Highlights

IM OBD Vechicles Readiness Exception List 
Technical Highlights

Over 30% Not Ready:Vehicles Already in Existing Appendix D 

The vehicles appearing in Table 3 below have been identified previously in the 

existing Appendix D that can be found in the June 2001 EPA document “Performing Onboard 

Diagnostic System Checks as Part of a Vehicle Inspection & Maintenance Program”. The 

document number of this report is EPA420-R-01-015. The recommended procedure for 

handling these vehicles is to scan them for MIL illumination without regard to readiness status. 

Table 3: Vehicles in June 2001 Appendix D 

Make Model 1996 1997 1998

Mitsubishi Diamante x x

Eclipse x x x

Galant x x x

Mirage x x x

Montero x x x

3000 x x

Saab 900/9000 x x

Subaru Impreza x

Legacy x

 The June 2001 Appendix D recommends All Model Mitsubishi vehicles from MY96-98 be scanned for MIL 

illumination without regard to readiness. The vehicles in Table 3 were only those that were identified in the state 

CY05 data, but this guidance update does not supersede that recommendation and all MY96-98 Mitsubishis should 

continue to be scanned for MIL illumination without regard to readiness. 

IM OBD Vechicles Readiness Exception List 
Technical Highlights

Over 30% Not Ready: Under Evaluation 

The vehicles listed below in Table 4 are the subject of ongoing lab testing and 

discussions with the auto manufacturers to determine the extent of the readiness problem in 

each case and develop a recommended handling procedure. Engine information is provided 

as available and should be used accordingly as some models exhibit readiness problems while 

those with a different engine do not (e.g. only the 2.0 L Sonatas appear to have a problem with 

readiness). 

Until further notice, states may chose to OBD test these vehicles regardless of their 

readiness status or default them to a tailpipe test. Any other options a state may wish to pursue 

should be discussed with EPA’s Office of Transportation & Air Quality. 

Table 4: Lab Testing or OEM Discussion Vehicles 

MY

Make Model 1996 1997 1998 1999 2000 2003

Chevy Tracker x x

Dodge Viper x

Ford Probe GT x x

Hyundai Accent

Elantra

Sonata

x x

x x

x x x

Kia Sephia

Sportage

x

x

Mazda Protege x

Plymouth Breeze x

Porsche 911 x x

Suzuki Sidekick x

Volvo 850 x x

S70 x

S90 x

V70 x

VW Passat x

 The June 2001 Appendix D recommends MY96-97 Volvo 850s be treated as non-problematic vehicles. However, 

based on this analysis of CY05 state data, these vehicles are exhibiting a high degree of not readiness despite the 

existing TSBs to address this problem. Therefore, the MY96-97 Volvo 850s have been listed in Table 4 as vehicles in 

need of further study. The same is true for the MY98 Volvo S70, S90 & V70. 

IM OBD Vechicles Readiness Exception List