Gas and Alternative Fuel Emissions Requirements

The regular inspection of auto emissions is an important part of protecting the air we breathe! Colorado’s current emissions program applies to most vehicles in Boulder County. With few exceptions, all gasoline-powered, hybrid, and alternative fuel vehicles require emissions inspections once they are over seven years old.

Emissions Requirements

Unless a vehicle is exempt (see below), the following requirements apply:

• Gas, hybrid, and alternative fuel vehicles require an emissions test. Starting in their 8th model year (2017 vehicles or older in 2023), vehicles must pass an emissions inspection in order to be registered in Boulder County. Testing is required when a vehicle changes ownership in their 7th model year or later (even if there is time left on the previous test, 2017 vehicles in 2023) and for registration renewal, if indicated on the renewal notice. Additionally, this is the frequency of testing:
  • 1982 and newer require an emissions test every two years.
  • 1981 and older require a test annually.
  • 1976-1989 with collector plates require a test every 5 years.
• Hybrid vehicles are required to obtain an Onboard Diagnostic (OBD) emissions inspection.
• Alternative fuel vehicles require a test. The following single/dual alternative fuel types can be tested at Air Care Colorado:
  • Ethanol
  • Natural Gas
  • Propane
  • Methanol
  • Bio-diesel
  • Propane/gas
  • Methanol/gas
  • Natural gas/diesel
  • Natural gas/gas
  • Ethanol/gas

Emissions Exemptions

The following vehicles are exempt from emissions requirements:

• Gas, hybrid, and alternative fuel vehicles are exempt for the first seven years. In 2025, this means vehicles that are 2019 or newer are exempt.
  • Exception: If vehicle ownership is being transferred in the last year of the seven-year exemption, an emissions test will be required. In 2025, this means that a 2019 vehicle will require an emissions test if there is a transfer of ownership.
• Vehicles 1975 and older with collector plates
• Vehicles 1976 or newer that have been grandfathered (i.e. registered as a “collector’s item” prior to September 1, 2009 and registration has never lapsed/expired/or had a change of ownership)
• The following vehicle types are exempt: kit cars, all-electric vehicles, motorcycles, horseless carriages, and vehicles registered as street rods

Emissions Testing for Registration Renewal

Obtain an emissions test if the statement “Emissions Test is Required” appears on your vehicle registration renewal notice.

• Emissions test results will be electronically posted to your vehicle registration record within minutes.
• Wait about 5 minutes after completion of your test and then renew your registration online or at a MV Express kiosk.

Where to Test Your Vehicle

Gas-fueled vehicles, hybrid vehicles, and some alternative-fueled vehicles can obtain an emissions test from Air Care Colorado.

• Monday – Friday: 8 a.m. – 5:30 p.m.; Saturday: 8 a.m. – 1 p.m.
• Locations and Map
  • Local Testing Locations:
    • Boulder: 5655 Airport Boulevard
    • Longmont: 4040 Rogers Road
    • Broomfield: 11609 Teller Street
    • Dacono: 5222 Silver Peak Avenue
• Phone: 303-456-7090
• Cost: $25 for vehicle model years 1982 and newer. $15 for vehicle model years 1981 and older. Cash, personal checks, debit or credit cards are accepted

Air Care Colorado does not test diesel vehicles. Diesel vehicles have different requirements.

New Purchases

In Colorado, sellers and dealers must provide emissions testing.

• A private seller is required to provide the buyer with a passing emissions test at the time of sale if the vehicle requires emissions testing. An emissions test that has been used previously for the purpose of vehicle registration/renewal cannot be transferred to the buyer.
• Colorado dealers are required to provide a passing emissions test or a voucher good for one emissions test at the time of sale if the vehicle requires an emissions test. These vouchers are typically only good for the first three days after purchase, so the buyer has a short window of time in which to get the vehicle tested and return it if it does not pass.