Skip to main content
An Official Vermont Government Website

ON BOARD DIAGNOSTICS (OBD II)

On board diagnostic (OBD) systems were developed in the 1980s by vehicle manufacturers to help technicians diagnose and service the computerized engine management systems of modern vehicles. A new generation of these systems, OBD II, is present on 1996 and newer vehicles. 

For more information on Readiness, Warranty, OBDII and Recall information visit vt-avip.com

FAQs.

I have an Agriculture plate, do I need to get an inspection?

Yes, see 23 V.S.A. § 1222 Inspection of registered vehicles

Are emissions system repairs covered by the vehicle manufacturer warranty?

Depending on the model year and mileage of your vehicle, emissions system repairs may be covered by the vehicle manufacturer. Vermont law requires that a vehicle’s entire emissions control system be warranted for a minimum of 3 years or 50,000 miles. Warranty coverage for the more expensive emissions control components is extended to at least 7 years or 70,000 miles, and the catalytic converter is covered up to 8 years or 80,000 miles. Some vehicles’ emissions control systems are warranted up to 15 years or 150,000 miles! Be sure to check your owner’s manual or warranty booklet! For more information on warranty coverage visit: http://dec.vermont.gov/ sites/dec/files/aqc/mobilesources/documents/ Warranty.pdf

Is there a grace period for Vehicle Inspection?

No

What if my vehicle has an emissions problem?

Have your emissions problem diagnosed and determine if the repair is covered under emissions warranty. You will need to make the repair and return for a re-test to get a pass sticker.

Why do we have emissions testing?

Federal law requires Vermont to have an emissions testing program. Ensuring your vehicle is in proper working order allows for;

  • Early detection of defects that lead to repairs that improve vehicle performance and fuel economy.
  • Repairing a defect before it gets worse saves money.
  • Protecting our environment and our health by identifying vehicle problems that cause increased air pollution.
What are some possible reasons for failing the OBD check on a vehicle inspection?
  1. The vehicle’s OBD system connector has been removed or is otherwise not working properly. The OBD check cannot be completed if the connector is missing or is not working properly. 
  2. The Malfunction Indicator Light does not illuminate when the ignition key is turned to the “on” position. When the vehicle’s OBD system detects a problem, it turns on the warning light to alert the driver of a problem. However, if the light cannot illuminate because the bulb has burned out or is otherwise not working, the driver would not be alerted to the problem. 
  3. The Malfunction Indicator Light on the instrument panel is on (and/or commanded by the vehicle’s onboard computer) while the engine is running. This indicates that the OBD system has identified a problem that must be repaired. In this case, one or more diagnostic trouble codes will also be reported by the vehicle’s OBD system and these codes will help your technician diagnose and repair your vehicle. 
What equipment is needed to inspect OBD Systems?

A scan tool with generic OBD II capability is necessary to perform the required check. A scan tool is a very useful device which is commonly used to assist in the diagnosis and repair of a variety of vehicle problems. Many inspection stations already own scan tools which can also be used to perform the required OBD check, but those inspection stations which do not will need to have one in order to inspect 1996 and newer vehicles. At a minimum, scan tools must be capable of :

  1. automatic initialization with any vehicle,
  2. determining readiness status of OBD monitors,
  3. determining malfunction indicator light status, and
  4. retrieving diagnostic trouble codes.

Any scan tool which complies with Society of Automotive Engineers Recommended Practice J1978 is acceptable. Scan tools are available from a number of well known equipment manufacturers.