Update: On Jan. 16, 2025, the Colorado Air Quality Control Commission adopted the measure described on this page. The commission publishes final rule language in the public register on its regulations web page. Read more in CDPHE's press release.
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Proposals for regulatory changes for motor vehicle inspection programs
In 2024, the division proposed changes to Colorado’s regulations regarding vehicle inspection programs. These include Colorado Air Quality Control Commission Regulations 11 and 12.
In January 2025, the commission adopted the proposed changes to both regulations.
Regulation 11, Automobile Inspection and Readjustment (AIR) program
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. This update will provide extra convenience for gasoline-vehicle owners and help the state further protect its clean air.
Heavy-duty trucks from model year 2008 and newer will also switch from the Two-Speed Idle (TSI) test to the OBD test, ensuring a more accurate evaluation of nitrogen oxides (NOx) emissions. This is important because NOx emissions are a major contributor to ground-level ozone pollution in Colorado.
Additional changes include:
- Implementing enhanced and modernized vehicle emissions testing process in Colorado.
- Adopting new technology that improves testing efficiency, procedures, accessibility, and accuracy of testing.
Regulation 12: Reduction of Diesel Vehicle Emissions
The commission approved changes to Regulation 12, which impacts owners of diesel-powered vehicles in the Diesel Program Area. This area includes all or portions of Adams, Arapahoe, Boulder, Broomfield, Denver, Douglas, El Paso, Jefferson, Larimer, and Weld counties. Regulation 12 Parts A and B require operators of diesel fleets with nine or more vehicles that self-test and certify compliance to use certain procedures and meet requirements for private testing stations.
The updates to Part A add:
- A visual inspection for emission control components for self-certification test vehicles.
- Training and qualification requirements for self-certification inspectors consistent with the requirements in Part B.
The commission also approved:
- New, more stringent opacity requirements in Parts A, B, and C to reflect the performance capabilities of newer diesel vehicles. The opacity standard for diesel vehicles has been lowered from 40% to 20% opacity measured over five seconds.
- Additional procedures designed to identify tampering as a result of engine replacements.
- Various clean-up of existing provisions to improve readability and clarity of the requirements.
Public meetings
In September 2024, the division hosted public meetings to discuss proposed changes to Regulations 11 and 12. The division considers feedback received during these meetings while preparing rule proposals.
Language interpretation services are available upon request. Registration is required.
- Virtual meeting: Tuesday, Sep 17, 2024, 10 a.m.-12 p.m.
- Virtual meeting: Wednesday, Sep 18, 2024, 6-8 p.m.
- Virtual meeting: Saturday, Sep 21, 2024, 10 a.m.-12 p.m.
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Contact us
Questions? Email cdphe_mobile@state.co.us.