# Colorado — Vehicle emissions testing: which counties require it, in which states

For Colorado, counties where testing is required is all or portions of Adams, Arapahoe, Boulder, Broomfield, Denver, Douglas, Jefferson, Larimer, and Weld counties; vehicles covered / exempt is owners of gasoline-powered vehicles in the Front Range area of Colorado; recent or pending change is Starting in 2026, these Colorado drivers will have access to self-service kiosks for On-Board Diagnostics (OBD) emissions tests that will be available 24/7 at convenient locations; program / authority is Automobile Inspection and Readjustment (AIR) program, verified against its source on 2026-08-18.

- **State:** Colorado _(our reading, not quoted from the source)_
- **Counties where testing is required:** all or portions of Adams, Arapahoe, Boulder, Broomfield, Denver, Douglas, Jefferson, Larimer, and Weld counties _(verified: appears in the quote below)_
- **Vehicles covered / exempt:** owners of gasoline-powered vehicles in the Front Range area of Colorado _(verified: appears in the quote below)_
- **Recent or pending change:** Starting in 2026, these Colorado drivers will have access to self-service kiosks for On-Board Diagnostics (OBD) emissions tests that will be available 24/7 at convenient locations _(verified: appears in the quote below)_
- **Program / authority:** Automobile Inspection and Readjustment (AIR) program _(verified: appears in the quote below)_

## What the source says

> The commission approved of updates to Regulation 11, which applies to owners of gasoline-powered vehicles in the Front Range area of Colorado. This area includes all or portions of Adams, Arapahoe, Boulder, Broomfield, Denver, Douglas, Jefferson, Larimer, and Weld counties. Starting in 2026, these Colorado drivers will have access to self-service kiosks for On-Board Diagnostics (OBD) emissions tests that will be available 24/7 at convenient locations.

## Source

- https://cdphe.colorado.gov/apcd/motor-vehicle-emissions

Last verified: 2026-08-18. Review by: 2027-08-18.
Part of [Vehicle emissions testing: which counties require it, in which states](https://referencesource.org/vehicle-emissions-testing-by-state/).