Driving Extension for Readiness Result | Repair Your Vehicle | Repair Tips | Retesting Tips |
Diagnostic Trouble Codes | Waiver Criteria | Waiver Applications and Exemption Requests

Failed Vehicles

A failed test result means your vehicle has not met U.S. Environmental Protection Agency emissions standards. Because emissions from a failing vehicle contribute to ozone formation, additional repairs are necessary until the vehicle passes, or until all requirements for a cost-based waiver are met. For more information see Waiver Criteria.

Driving Extension for Readiness Result: Fail

Beginning Aug. 28, 2008, motorists whose vehicles fail the On-Board Diagnostics, or OBD, test only because the vehicle's readiness monitors are unset are now legally permitted to drive their vehicle for up to 30 days beyond the expiration of their vehicle's registration for the purpose of resetting the vehicle's readiness monitors. Motorists should keep a copy of the most recent failing OBD test results with them to present to law enforcement officers as proof that they are operating the vehicle to reset the vehicle's readiness monitors. Even though this new law does give motorists additional time to complete their vehicle emissions inspection, the department recommends that motorists begin the vehicle emissions inspection process as soon as they receive their vehicle registration renewal notice so that they can register their vehicle on time and avoid the late registration penalty.

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Repair Your Vehicle

Where can I go to have my vehicle repaired?
Motorists are not required to have emissions repairs completed at the station that performs their vehicle’s emissions test.  Anyone, including the motorist themselves, can perform emissions repairs. The vehicle owner's choice of who does the emission repair may affect their ability to obtain a waiver though. See Waiver Criteria for more information.

A pre-repair emissions inspection that reports both the Diagnostic Trouble Codes, or DTCs, that are commanding the malfunction indicator lamp, or check engine light, to illuminate or other items causing an emissions inspection failure is required before any emissions repairs are made should the vehicle eventually require an emissions waiver.  The GVIP emissions inspection report should be provided to whoever is performing the repairs to ensure they understand, and focus their attention on, correcting the causes of the emissions failures reported to the state.

Any emissions-related repair made must be qualified as necessary to correct the cause of the related emissions failure by the person performing it for those repairs to be accepted toward a waiver. An emissions system monitor reporting ‘Not Completed’ does not indicate a need to repair or replace the related emissions components.  A written explanation of the diagnostic work performed by a skilled automotive technician, using the appropriate diagnostic tools and following manufacturer determined diagnostic procedures specific to the cause of the failure, is the best method for qualifying an emissions repair. If the motorist repaired the vehicle, or directed the shop to perform the repairs, the burden of qualifying those repairs is up to the motorist should a waiver be sought.  

A post-repair inspection should be performed only after all required emissions system monitors are ‘Completed/Ready’ (see readiness on the On–Board Diagnostics fact sheet).  Generally, driving the vehicle for three to five days under normal city and highway driving conditions will allow the monitors to reset and the vehicle’s emissions control computer to evaluate the effectiveness of the repairs.  If the post-repair inspection is a fail solely for the ‘Readiness Result’ part of the inspection after having driven the three to five days suggested, return to the shop that performed the repairs and see what they can do to help.   If the post-repair inspection is a fail for the DTC that the repair was made for, the motorist should return the vehicle to whoever performed those repairs, show them the inspection fail document and inquire about any repair guarantee or warranty the shop may have, especially if diagnostic work was obtained from the shop performing the repair.  If it is a fail for a different DTC, it is possible that fixing the cause of the initial DTC allowed the system to do further self-testing resulting in additional DTCs being reported.  You should ask the person that performed your repairs to check over their work to ensure nothing was missed, and if additional repairs are needed, make a decision on whether to make more repairs or, if the minimum required waiver amount has been spent, elect to submit a cost-based repair waiver. 

Motorists are encouraged to contact the department at 314-416-2115 with any questions or concerns regarding the emissions inspection or the repair and waiver process.   Motorists are encouraged to report automotive repair facilities that fail to provide qualified emissions repairs to the Attorney General’s Office – Consumer Fraud Division at 800-392-8222 or http://ago.mo.gov and the Better Business Bureau at 314-645-3300 or http://stlouis.bbb.org/.

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Repair Tips

Check your vehicle’s warranty.
Your repairs might be covered by a manufacturer’s warranty. For details, consult your vehicle owner’s manual or contact a dealership.

Find a repair technician.
Anyone may repair your vehicle. Customers are not required to have repairs completed at the station that performs their emissions test. However, labor costs can only be applied toward a cost-based waiver if the work was completed by a Missouri Recognized Repair Technician, or MRRT, since these technicians meet industry-recognized standards for emissions-related repair knowledge. For a current listing of shops employing a MRRT, see Missouri Recognized Repair Technicians.

Bring the paperwork.
After the emissions test you received a Vehicle Inspection Report, or VIR. Give these papers to your repair technician and make sure whomever performs the repairs correctly fills out and signs a Repair Data Sheet. Your vehicle will not be retested without this information.

Talk with your repair technician.
Your repair technician should diagnose what’s wrong, discuss the repairs your vehicle needs, and make sure you get the most effective repairs for the money spent. Finally, remember to ask the repair technician to confirm that your vehicle’s readiness monitors are reset to ready.

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Retesting Tips

Once your vehicle has been repaired, it’s time for a retest. Retests are required until either your vehicle passes or until you obtain a cost-based waiver from the Missouri Department of Natural Resources.

Know your time limits.
When repairs are completed, you must return to the initial testing station within 20 business days to qualify for one free reinspection. After 20 business days, you will be required to pay the full emissions test fee again.

The vehicle owner must present to the station the previous vehicle inspection report and the completed repair data sheet that your repair technician filled out and signed. Your passing emissions test is valid for registration purposes for 60 days from the date the vehicle passes the test or receives a cost-based waiver.

Before you retest…
Drive your repaired vehicle normally for several days before returning to the station that initially performed the emissions                 test. Doing so can help reset your vehicle’s readiness monitors. For more information see readiness.

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Diagnostic Trouble Codes

What are Diagnostic Trouble Codes?
Diagnostic Trouble Codes, or DTCs, are vehicle generated-OBDII codes that can trigger a malfunction indicator light, or MIL. Each numeric code corresponds with a specific emissions-related concern. All emissions system components that caused DTCs to appear must be repaired in order for the vehicle to pass.

The Vehicle Inspection Report, or VIR provided at time of failure will list the DTCs recorded from the vehicle’s OBDII computer. Not all DTCs that trigger the MIL may be listed on the VIR. Manufacturer specific DTCs (P1###) are listed, but not defined, on the VIR as the definitions vary between manufacturers.

You should not replace emissions control components based solely on the DTCs stored in the vehicle’s OBDII system. A proper diagnosis by an OBDII trained or experienced technician is needed to positively identify the causes of the current OBDII test failure.

Repair technicians may choose to clear the DTCs electronically after the repair. This process will reset the emissions system monitors to Not Ready. Your repair technician should assist you in taking the necessary steps to reset the monitors to Ready. On the other hand, repair technicians may choose to perform a repair and then leave the check engine light illuminated. After the vehicle performs the required drive cycles to verify that the condition causing the DTC has not reoccurred, the OBDII system will turn the check engine light off. You can then return to the station for an emissions retest.

Before your vehicle can be retested, all required emissions system monitors must have a Ready status noted. Please discuss with your repair technician about how you can tell when your vehicle is ready to be retested.

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Waiver Criteria

There are three types of emission inspection waivers available to vehicle owners.  These are: Cost-Based (for vehicles that fail the emissions inspection), Out-of-Area (for vehicles located in Missouri), and Reciprocity (for vehicles located outside of Missouri). All Waiver Applications must be submitted to the department. Staff will contact you within five business days of receipt of the waiver application regarding the status.  The costs of repairs made to correct missing or damaged emissions control components (example: catalytic converters, air pumps, etc.) or “MIL-KOEO, Data Link Connector, or DLC, or OBD Communication” emissions inspection failures cannot be applied toward an emissions inspection waiver.

COST-BASED WAIVERS                          

There are two types of repair related cost-based waivers:

1) for vehicles that have had repair work done at a licensed automotive repair business;and,

2) for vehicles that have had repair work performed solely by the vehicle owner. 

The amount of money required to be spent on either is explained in the ‘Repair Waiver Costs’ section.  Applications for either may be found at the bottom of this page. 

A Cost-Based Repair waiver is available when:

1) the vehicle failed a pre-repair GVIP emissions inspection where the Vehicle Inspection Report, or VIR, listed the DTCs causing the malfunction indicator light, or MIL, to illuminate, and other emissions inspection failures;

2) qualified repairs* to correct the causes of the DTCs reported on the pre-repair inspection are made;

3) the cost of the qualified repairs exceeds the dollar amount noted in the ’Repair Waiver Cost’ paragraph that follows; and

4) the vehicle failed a post-repair GVIP emissions inspection where the VIR reported a “Pass” for the Readiness Result, MIL-KOEO, DLC, and OBD Communications parts of the inspection, but a DTC Result: Fail. 

*A qualified repair is one that pre- and post-repair diagnostic data or post-repair inspection results support as having been necessary to correct the cause of the DTCs reported on the pre-repair VIR. 

A Cost-Based Estimate waiver is available to a vehicle that has failed a current GVIP emissions inspection where:

1) the latest GVIP VIR recorded on a single DTC and a "Pass" for the Readiness Result, MIL-KOEO, DLC, and OBD Communication portions of the inspection;

2) a diagnosis following manufacturer developed diagnostic processes of the cause of the DTC has been obtained from a shop employing a Missouri Recognized Repair Technician or one that specializes in the cause of the failure (example: transmission shop);

3) the total estimated cost of the repair to correct that DTC is greater than $450; and,

4) a write-up of the diagnostic work and estimate of costs is provided on an invoice from the shop doing that work.

The invoice from the shop performing the diagnostic testing must include:

a) a written explanation of the diagnostic testing done and the test results obtained that support the repair determined to correct the cause of the DTC; and,

b) the estimate, broken down into parts and labor, for the repair that would correct it.  

A Cost-Based Estimate waiver approval obligates the motorist to correct the cause of the diagnosed DTC by the next inspection for registration cycle, as documented by a GVIP emissions inspection performed at that time, to be eligible for an emissions inspection pass or repair waiver.

Repair Waiver Cost.  A motorist must spend a minimum of $450 on qualified emissions-related parts at a licensed automotive repair business, unless the repair work is performed by a Missouri Recognized Repair Technician, in which case both qualified parts and labor may be applied toward the waiver A vehicle owner who performs the repairs themselves must spend at least $400 on qualified EPA approved and listed, emissions-control parts. See the Cost-Based Waiver Applications below for specifics.

A vehicle owner who is financially dependent solely on state and federal disability benefits and other public assistance programs, and whose vehicle fails a pre- and post-repair emissions inspection with DTCs reported, may receive a reduced-cost repair waiver. The vehicle owner must provide a completed Financial Waiver Eligibility Request Form along with a copy of the vehicle title and proof of their approval for state or federal disability to be considered for this reduction. The vehicle owner must also submit a Cost-Based Repair Waiver application and all required repair documentation, after having spent at least $200 on qualified parts, and if applicable repair labor.


An Out-of-Area waiver is available for a vehicle when it is:

1) registered in either the City of St. Louis or the counties of St. Louis, St. Charles, Jefferson and Franklin;

2) currently located in the State of Missouri; and

3) currently, and for the next 24 months will be operated exclusively outside of the City of St. Louis or the counties of St. Louis, St. Charles, Jefferson and Franklin. 

Owners must apply to the department for consideration of an out-of-area waiver.  The department reserves the right to investigate any request received. See Out of Area Waiver Request to apply.

A Reciprocity waiver is available for an emission inspection only required vehicle (one that is five years old or less) provided it is located outside Missouri, but in a state that conducts pass/fail OBD testing. You may contact the department for a list of these states. The motorist may obtain a vehicle emission inspection in that state and submit a copy of the inspection and a completed Reciprocity Waiver application to the department. Approval of the Reciprocity Waiver will allow the vehicle to be registered.    


Owners of vehicles required to document both emissions and safety inspection compliance for registration purposes, but are located outside the state of Missouri for 60 days or more prior to the registration renewal date, can print Department of Revenue General Affidavit Form 768 (available at www.dor.mo.gov).  The vehicle owner must check Box 3 of this General Affidavit form, fill out the vehicle information section, and submit this form with the registration renewal application directly to the Department of Revenue.  The vehicle must obtain and be able to document both safety and emissions inspection compliance within 10 days of returning to Missouri to avoid enforcement action and penalties.

For more information see Waiver Exemption poster and Frequently Asked Questions About Emissions Waivers.

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Waiver Applications and Exemption Requests

Vehicle owners must apply for all emissions related waivers and exemptions to the Missouri Department of Natural Resources.  Vehicle owners may write to Missouri Department of Natural Resources, Gateway Vehicle Inspection Program, 7545 S. Lindbergh, Suite 210, St. Louis, MO 63125 or call 314-416-2115 with any questions or concerns.

Note icon.Once a request is received, motorists will be notified in writing of the approval or denial of their request. If the request is approved, the motorist will not be required to take further action as this department will notify the Department of Revenue electronically of the approval. If the request is denied, then the motorist will be required to have their vehicle emissions tested. The department is not responsible for any penalties associated with late registration due to failure to submit an exemption or waiver request in a timely manner.

Cost-Based Waiver Application Affidavit - Repairs Made by a Repair Technichian, Form--MO 780-1971

Cost-Based Waiver Application Affidavit - Repairs Made by a Vehicle Owner, Form--MO 780-1973

Estimate-Based Waiver Application Affidavit - Estimate Provided by a Vehicle Repair Technician, Form--MO 780-1994

Mileage-Based Exemption Request, Form--MO 780-1972

Out of Area Waiver Request, Form--MO 780-2202

Reciprocity Request - Emissions Inspection, Form 780-2192

Financial Waiver Eligibility Request, Form--MO 780-1970

For more information see Frequently Asked Questions About Emissions Waivers.


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