Frequently Asked Questions

Your vehicle must be inspected prior to the expiration of your tags. Your certificate of compliance is valid for 90 days from the date of the test, so you will have plenty of time to have your vehicle inspected (and repaired if needed) prior to the expiration of your tags. Even though you get one free retest within 90 days of the initial test, this does not allow you to operate your vehicle with expired tags.

If you have your vehicle tested PRIOR TO THE EXPIRATION OF YOUR TAGS, and it fails, you are allowed a 30-day grace period from the date your tags expire in which you have your vehicle repaired, receive a passing emissions test and renew your tags.

You may take your vehicle to any of the test stations located in Middle Tennessee. Please click here

The test fee is $9.00.

Inspection stations are typically the busiest during the first and last week of each month and the middle of the day (10-2). The best times to get your vehicle tested are generally the middle two weeks of the month and early and late in the day.

Repairs can be made anywhere. However, we strongly encourage the use of a qualified repair person knowledgeable about your vehicle and its emission control system. No matter where your vehicle is repaired, you are entitled to one free retest within 90 days of the initial test. Even though you get one free retest within 90 days of the initial test, this does not allow you to operate your vehicle with expired tags.

Exemptions: The only vehicles that are exempt from testing in Nashville are new motor vehicles being registered for the first time, heavy duty motor vehicles (greater than 10,500 pounds GVWR), motorcycles, antique motor vehicles, electric powered light-duty motor vehicles (excluding all hybrid vehicles) and gasoline-powered light-duty motor vehicles with a designated model year prior to 1975.

Age: Motor vehicles 1974 and older are exempt from the vehicle testing program.

Antique cars: Vehicles over 25 years old which are solely owned as a collectors’ item and used for participation in club activities, exhibits, tours, parades and similar uses, but in no event for general transportation, are exempt from the vehicle testing program.

Reconstructed and homemade vehicles: These vehicles are inspected for emissions compliance using the standards and test procedures applicable for exhaust emission, functional emissions control devices, and visual inspection for each individual vehicle – based on the engine year of the engine installed in the vehicle.

Vehicles with exchanged engines: These vehicles are inspected for emissions compliance based on the chassis model year of the vehicle. However, if the engine is newer than the chassis model year, the emissions inspection is based on the model year of the engine.

Vehicles with engines changed from one fuel type to another fuel type (for example, from a diesel engine to a gasoline engine) that are subject to these regulations are subject to tests and standards for the current fuel type of the engine installed.

All trucks and vans: Trucks and vans are to be tested according to standards as determined by the manufacturer’s gross vehicle weight rate (GVWR). If no manufacturer’s GVWR is available, the vehicle shall be tested according to the GVWR as determined by the Nashville VIP.

New motor vehicles being registered for the first time are exempt from the vehicle testing program.

Age: Light duty vehicles (10,500 lbs., or less, GVWR) with a model year of 1975 and newer are subject to the vehicle testing program. Vehicles with a model year of 1974 and older do not have to be tested.

Antique cars:: Vehicles over 25 years old which are solely owned as a collectors’ item and used for participation in club activities, exhibits, tours, parades and similar uses, but in no event for general transportation, are exempt from the vehicle testing program.

Your vehicle must be repaired and retested. You may receive a free retest after having your vehicle repaired if you present it for retest within 90 days of the original test date. Even though you get one free retest within 90 days of the initial test, this does not allow you to operate your vehicle with expired tags.

Light duty gasoline vehicles with a model year of 1975 – 1995 receive a tailpipe emissions test and a tampering inspection which includes the catalytic converter and the fuel filler cap. Light duty gasoline vehicles 1996 and newer receive an OBD test and a tampering inspection including the catalytic converter, data link connector check and a fuel cap pressure test. Light duty diesel vehicles with a model year of 1975 – 2001 receive a Curb Idle (Opacity) test and a tampering inspection which includes a catalytic converter check, if applicable, and a fuel cap check. Light duty diesel vehicles 2002 and newer receive an OBD inspection and a tampering inspection including the catalytic converter, if applicable, data link connector check and a fuel cap check.

Your vehicle must pass all portions of the inspection (Emissions, Tampering and Gas Cap) to pass the overall inspection.

When returning for a retest, 1975 – 1995 gasoline vehicles and all diesel vehicles will be subject to the entire anti-tampering and appropriate emissions test. 1996 and newer gasoline vehicles will only be subject to the portion of the inspection which the vehicle originally failed.

If the vehicle fails the retest, a vehicle inspection report will be provided indicating the reason(s) for failure. The vehicle must have the necessary repairs made in order for the vehicle to pass the vehicle inspection.

You are free to select a qualified repair technician or repair the vehicle yourself. However, due to the complexity of today’s vehicles, you should strongly consider having your vehicle repairs performed by a qualified technician who is experienced in diagnosing and repairing vehicle emissions systems.

The Nashville VIP provides a free diagnostic service to Davidson County vehicle owners whose vehicle has failed the vehicle inspection. Under no circumstances will we repair the vehicle. This free service is offered by appointment only by calling the Metro Public Health Department.

You are free to select a qualified repair technician or repair the vehicle yourself. However, due to the complexity of today’s vehicles, you should strongly consider having your vehicle repairs performed by a qualified technician who is experienced in diagnosing and repairing vehicle emissions systems.

Kit cars: Vehicles manufactured as kit cars may receive an alternate type of inspection.

Reconstructed and homemade vehicles: These vehicles are inspected for emissions compliance using the standards and test procedures applicable for exhaust emission, functional emissions control devices, and visual inspection for each individual vehicle – based on the engine year of the engine installed in the vehicle.

Vehicles with engines changed from one fuel type to another fuel type (for example, from a diesel engine to a gasoline engine) that are subject to these regulations are subject to tests and standards for the current fuel type of the engine installed.

As long as they weigh 10,500 pounds (GVWR) or less, trucks and vans are tested according to standards as determined by the manufacturer’s gross vehicle weight rate (GVWR). If no manufacturer’s GVWR is available, the vehicle shall be tested according to the GVWR as determined by the Nashville VIP. Currently, vehicles weighing more than 10,500 pounds GVWR are exempt from testing.

Yes, light duty diesel powered vehicles weighing 10,500 lbs. or less GVWR are inspected in the Nashville Vehicle Inspection Program.

OBD or On-Board-Diagnostics have been around since 1980, when General Motors first introduce the system in certain vehicles sold in California. Chrysler and Ford soon followed GM. By the mid 1980’s, the Asian and European manufacturers were installing on-board computer systems for the purpose of controlling emissions. With the increasing smog problem nationwide, every light duty vehicle sold in California in 1988 had to comply with the new OBD-I (first generation) regulations. The intent was to gain consistency in the way emission systems were being monitored and how emissions problems could be brought to a driver’s attention.

The OBD-I regulations for 1988 required onboard computer systems to have the ability to record and store a specific diagnostic trouble codes for malfunctioning sensors or systems. The major requirement of OBD-I was to notify the driver of a malfunction by having the on-board computer turn on the MIL or Malfunction Indicator Lamp more commonly known as the “Check Engine” or “Service Engine Soon” light.

The 1990 Clean Air Act Amendments adopted the new OBD-II (second generation) requirements. These new requirements were implemented for every vehicle sold in the U.S starting in model year 1996. The requirements included the following:

• Use of the same universal Diagnostic Link Connector in every light-duty vehicle sold in the U.S.
• A standard location for the Diagnostic Link Connector
• A standard list of Diagnostic Trouble Codes (DTC)
• Common diagnostic test modes
• The ability to record a snapshot
• The ability to store a code when an emissions failure occurs
• A standard glossary of terms

Gasoline powered vehicles model years 1996 and newer, and diesel powered vehicles model years 2002 and newer, will require an OBD-II test.

The inspector will connect a communication cable from the emissions analyzer to the Diagnostic Link Connector located in your vehicle. No changes to your vehicle will be made; only data from your vehicles computer will be downloaded to the emissions analyzer.

Your vehicle will fail the OBD-II test if the Malfunction Indicator Lamp (Check Engine) light is illuminated.

For 1996 – 2000 light duty gasoline vehicles (not more than 10,500 lbs. GVWR), if more than 2 supported readiness monitors are not set (not ready), the OBD test cannot be completed. If the vehicle originally failed for catalyst failure (visual or diagnostic trouble code), then the catalyst monitor must pass the readiness test.

For 2001 and newer light duty gasoline vehicles (not more than 10,500 lbs. GVWR), if more than 1 supported readiness monitor is not set (not ready), the OBD test cannot be completed. If the vehicle originally failed for catalyst failure (visual or diagnostic trouble code), then the catalyst monitor must pass the readiness test.

Readiness monitors must be set before a vehicle returns for a retest. If the supported monitors are not ready, then the vehicle will fail the OBD-II test.

The computer in your vehicle performs diagnostic tests on certain emissions systems while you are driving. These system monitors are usually set (ready or complete). Sometimes system monitors become “not ready” due to a problem with your vehicle, the battery in your vehicle having been disconnected or the computer having had its memory erased.

For 1996 – 2000 light duty gasoline vehicles (not more than 10,500 lbs. GVWR), if more than 2 supported readiness monitors are not set (not ready), the OBD test cannot be completed. If the vehicle originally failed for catalyst failure (visual or diagnostic trouble code), then the catalyst monitor must pass the readiness test.

For 2001 and newer light duty gasoline vehicles (not more than 10,500 lbs. GVWR), if more than 1 supported readiness monitor is not set (not ready), the OBD test cannot be completed. If the vehicle originally failed for catalyst failure (visual or diagnostic trouble code), then the catalyst monitor must pass the readiness test.

Readiness monitors must be set before a vehicle returns for a retest. If the supported monitors are not ready, then the vehicle will fail the OBD-II test.

You should have your vehicle serviced by a qualified technician. You are free to select a qualified repair technician or repair the vehicle yourself. However, due to the complexity of today’s vehicles, you should strongly consider having your vehicle repairs performed by a qualified technician who is experienced in diagnosing and repairing vehicle emissions systems.

The Nashville VIP provides a free diagnostic service to Davidson County vehicle owners whose vehicle has failed the vehicle inspection. Under no circumstances will we repair the vehicle. This free service is offered by appointment at the Metro Public Health Department.

If the Check Engine light is flashing or blinking, you should have your vehicle serviced as soon as possible. The flashing light may indicated that there is an engine misfire, and extensive driving with an engine misfire could damage your vehicle’s catalytic converter.

Yes. Some vehicles require extensive driving to reset certain system readiness monitors. Do not disconnect the battery on your vehicle. If your vehicle is in for service, ask your technician not to clear the computer’s memory since this will only unset the system readiness monitors and result in your vehicle failing the OBD-II test. Also, be sure your vehicle is at normal operating temperature when you arrive at the test center.

Diesel fuel, like gasoline, is petroleum based. However, diesel fuel is less refined then gasoline. Because it is less refined, small particles and solids from crude oil remain in diesel fuel. These solids are burned during the combustion process, which then become particulate matter released into the air from the vehicle’s exhaust. Routine aging and/or lack of maintenance can increase the amount of particulate matter from the exhaust of diesel vehicles. The normal emissions test performed on gasoline powered vehicles cannot measure particulate matter. Therefore, special measuring equipment is needed to perform the diesel emissions test. The equipment used, called an opacity meter, measures the density of diesel exhaust.

All light duty diesel powered vehicles weighing 10,500 lbs., or less, GVWR are required to be tested. 1975 – 2001 diesel vehicles will receive a Curb Idle (opacity) test, and 2002 and newer diesel vehicles will receive an OBD test.