Motor vehicle emissions

RSD Green Box

Rapidscreen Roadside Testing

RapidScreen roadside testing offers motorists of well-maintained, clean-running vehicles the opportunity to Skip the Trip to an emissions testing station.

RapidScreen data collection units (either housed in vans or green boxes) collect emissions-related data as vehicles are driven by them. The collection units are positioned at pre-determined, state-approved sites on highway on-ramps throughout the Front Range. As a vehicle passes the RapidScreen unit, a camera captures an image of the vehicle and license plate, and a process using infrared and ultraviolet light beams collects and measures the vehicle's emissions output. If the vehicle registers clean, this data is then matched to vehicle registration records, and a 'RapidScreen' message is added to the Vehicle Registration Renewal postcard alerting the driver that they have 'Passed Roadside Emission.'   

RapidScreen roadside testing units are rotated regularly to collect data from as many vehicles as possible. Click here to find unit RapidScreen Locations for the current and upcoming weeks. 

Gasoline-powered vehicle inspections 

SAVE TIME: Please attempt to register your vehicle online before visiting an emissions inspection station. Learn more at


General emissions inspection requirements and information

Check the registration renewal postcard that your county clerk mails to you about a month before your vehicle’s registration renewal is due.

  • If “EMISSIONS TEST REQUIRED” appears on the card, then you'll need to take your vehicle to an Air Care Colorado inspection station.
  • New vehicles are exempt from inspection for the first seven model years. A 2011 vehicle, for example, doesn't need an inspection until 2018.
  • Vehicles 8 through 11 years old will be inspected using onboard diagnostics (OBD).
    • If the “Check Engine” light is turned on, these vehicles will fail the inspection and need repairs.
    • Making repairs improves vehicle performance, extends vehicle life and saves money.
    • Learn more at EPA or National OBD Clearinghouse.
  • Vehicles manufactured beginning in 1982 that are at least 12 years old will be inspected using the  “I/M 240” dynamometer (treadmill) test.

    • In 2016, this requirement applies to model year 1982 through 2005 vehicles and so on.
    • A check engine light on a vehicle at least 12 years old may still pass if the I/M 240 test can be run and the car can pass the test. An advisory may be issued. 
  • Vehicles manufactured in 1981 and older will be inspected using a two-speed idle test.

  • Hybrid vehicles 8 years and older will be inspected using onboard diagnostics (OBD). As with all vehicles inspected, hybrids will also have their gas caps checked, and no visible smoke is allowed.

  • ​Most inspection stations now have at least two lanes dedicated to inspecting all-wheel-drive vehicles to accommodate the growing number of these vehicles.

  • RapidScreen roadside tests remain an important part of the program, allowing exceptionally clean vehicles to skip a trip to an inspection station. 

    • Owners of eligible vehicles will see “PASSED ROADSIDE EMISSIONS” on their registration renewal cards, and they won't need to go to an inspection station.

    • Current RapidScreen locations are posted on the Air Care Colorado website.

  • Air Care Colorado inspection stations accept cash, checks, Visa, MasterCard, and Discover.
  • Diesel-powered vehicles are inspected through a different program.

For more information, contact Air Care Colorado: 303-456-7090

Metro Denver and North Front Range emissions inspection

Notice of Emissions Liability Extension

With the passage of the Deter Tampering Motor Vehicle Emissions Control Systems Act (SB22-179), the period during which an auto dealer is liable for a recently purchased gas-powered motor vehicle's compliance with Colorado emissions standards has been extended from three to five business days after purchase. 

Beginning August 10, 2022, vehicle buyers must be informed of the extension when the emissions testing coupon is given to the customer to sign. New, updated vehicle emissions testing coupons will be available at the main Air Care Colorado office by August 31, 2022. Air Care Colorado will continue to honor the existing emissions testing coupons during the inventory transition. 

Please contact the Division of Motor Vehicles Emissions Team at 303.205.5603 if you have any questions. 

County requirements

  • You must have an emissions inspection done on any gasoline-powered vehicle when you register, renew registration for, or sell the vehicle within the Automobile Inspection and Readjustment (AIR) program area. The program area covers all or parts of the following counties:
    • Adams (west of Kiowa Creek)
    • Arapahoe (west of Kiowa Creek)
    • Boulder
    • Broomfield
    • Denver
    • Douglas
    • Jefferson
    • Larimer (Fort Collins, Loveland, Windsor, and surrounding mountain areas).
    • Weld (Greeley, Windsor and the I-25 corridor).
  • Vehicles registered to an address outside the program area but driven regularly into the program area (e.g., for work or school) must be inspected.

Inspections for 1982 and newer vehicles

  • An enhanced inspection is required every two years for 1982 and newer gasoline-powered light-duty vehicles (i.e. passenger cars and light trucks under 8,501 pounds GVWR).
  • Many vehicles can pass inspection by driving past the RapidScreen roadside unit found throughout the program area. 
  • Vehicle owners learn if they need an inspection (e.g., "EMISSIONS TEST REQUIRED") through the registration renewal cards they get from their county clerks.
  • Newer vehicles are exempt from inspection to the original owner for the first seven years. A 2020 vehicle, for example, won't need an emissions inspection until 2027.
  • Vehicles that are 8 through 11 years old get a test of their onboard diagnostic (OBD) computer systems.
  • AS OF JANUARY 2015: vehicles in this age range with their "Check Engine" light turned on will fail the inspection. They must be repaired and reinspected in order to pass.
  • AS OF JANUARY 2015: Hybrid and plug-in hybrid vehicles that are 8 years and older must have a test of their OBD computer systems. If these vehicles have their "Check Engine" light on, they will fail the inspection and must be repaired and reinspected in order to pass. 
  • Fully electric-powered vehicles (i.e., with no gas tank or tailpipe emissions) remain exempt from inspection. 
  • Vehicles that are 12 years and older will have their emissions tested on a dynamometer (a treadmill-like device that provides real-time emissions data). Hybrid vehicles aren't placed on the dynamometer.
  • The inspection can be done at any Air Care Colorado inspection stations
  • Collector vehicles are subject to different emissions requirements.
  • See the frequently requested information page or the Air Care Colorado website for additional information. 

Inspections for 1981 and older vehicles

A two-speed idle test is required every year for 1981 and older light-duty vehicles and all heavy truck. This test can be done at Air Care Colorado stations or independent licensed test stations.

Enhanced inspection expanded to North Front Range 

The Enhanced Vehicle Emissions inspection was expanded in 2010 to parts of Larimer and Weld counties to control ground-level ozone. 

RapidScreen Roadside Emissions Testing Program

To reduce the number of vehicles requiring a traditional emissions inspection, the RapidScreen roadside emissions testing program was established for Metro Denver and North Front Range. The RapidScreen program measures emissions and records license plate numbers as vehicles drive past roadside monitors. 

You can skip a trip to the Emissions Inspection Station if you are notified by mail that your vehicle passed RapidScreen. 


On Board Diagnostics (OBD) and being READY for an inspection

Every vehicle built for sale in the USA since model year 1996 has On Board Diagnostics (OBD). This feature helps find potential problems with the vehicle, leading to quicker repairs, improved performance, and better air quality. 

Make sure your vehicle is ready for the next inspection.

If you received an "Incomplete Inspection Report," it may be because:

  • Your OBD system had problems communicating with the station's test equipment


  • Your OBD system is "Not Ready" for an inspection. 

OBD monitors must be set to "Ready" before getting an inspection. Readiness monitors are set by a procedure known as a Drive Cycle. Some vehicle manufacturers include Drive Cycle procedures in the owner's manuals. In many cases, a few days of normal city and highway driving will complete the Drive Cycle and set the required monitors to "Ready." Many repair technicians can verify that the required readiness monitors are set to "Ready" or not. 

These Drive Cycles are complex and vehicle/monitor specific, and are not guaranteed to work for all vehicles due to varying circumstances. Please contact your vehicle maker for specific drive-cycle and other information about your vehicle. 

CDPHE operates several Emissions Technical Centers that can also provide assistance: 1-888-861-2646.

Here are some general resources if you want to try to make your vehicle ready on your own: 

Administration of the Automobile Inspection and Readjustment (AIR) Program

The Automobile Inspection and Readjustment (AIR) Program's purpose is to reduce motor-vehicle-related pollution through the inspection and emissions-related repair of gasoline-powered motor vehicles.


  • The program is administered jointly by our Air Pollution Control Division and the Colorado Department of Revenue.
    • The Air Pollution Control Division certifies the program, including testing procedures and equipment.
    • It works with the Air Quality Control Commission, the Regional Air Quality Council, the state Legislature, local governments, the U.S. Environmental Protection Agency (EPA) and others in assessing the effectiveness of the program and in determining program modifications.
  • The Department of Revenue administers the day-to-day operations, including:
    • Licensing of inspectors and test facilities.
    • Conducting field audits.
    • Investigating complaints.
    • Processing waivers.
    • Collecting revenues.
    • Working with county governments that issue vehicle registrations.

More information

Automobile Inspection and Readjustment Program Annual Reports:

Air Care Colorado 
Information on emissions testing, including station locations, fees, testing tips and what to do if your car fails.

Colorado Department of Revenue 
Answers to frequently asked questions about emissions testing.

Fuel economy website
From the EPA listing gas mileage, greenhouse gas emissions, air pollution ratings and safety information for new and used cars and trucks.

Contact the Mobile Sources Program

Please send questions/comments to  

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Emissions technical centers 

CDPHE operates emissions technical centers throughout the Denver Metro and North Front Range areas. These are multifunction facilities that conduct a variety of customer service and field activities to help vehicle owners and the repair industry meet emission requirements.

Emissions technical centers are especially helpful if your vehicle has already failed multiple emissions inspections. Their technicians are experts in identifying emissions-related problems, but they do not make any repairs.

Emissions technical centers serve motorists, independent and franchised auto dealers, automotive repair technicians, diesel fleet owners and operators, petroleum marketers, alternative-fuel vehicle converters and consumers, and the Colorado Department of Revenue.

Emissions technical centers also provide training and certification for repair technicians and emissions inspectors, and inspect to support the Diesel Emissions Control Program and the Oxygenated Gasoline Program.

Emissions technical centers evaluate vehicles by appointment only. Please contact the center nearest you to make an appointment: 

Emissions technical center locations

Aurora *
15608 E. 18th Ave.
Aurora, CO 80011

* The Aurora Emissions Technical Center also houses the High Altitude Test Facility that provides high altitude motor vehicle emissions testing, collects data for evaluation new strategies to reduce vehicle emissions, tests the emissions performance under a variety of conditions (wintertime driving, oxygenated and alternative fuels, etc.), and tests various emissions-control technologies.

Broomfield 11609 Teller St. 
Broomfield, CO 80020



Denver 2450 W. Second Ave.
Denver, CO 80223



Fort Collins 835 Southeast Frontage Road
Fort Collins, CO 80524
Greeley 2844 W. 30th St.
Greeley, CO 80631
Highlands Ranch 8498 S. Colorado Blvd.
Littleton, CO 80126

Building use criteria

Emissions Technical Centers (ETCs) are state-operated facilities with duties specified in state law to provide support to various Mobile Sources program activities. This includes support to the Gasoline and Diesel emissions inspection programs, fuel sampling and analysis, field inspections and enforcement, and the training and testing of inspection and repair technicians, among other responsibilities.

Requests routinely come from automotive trainers, training committees, vocational schools, industry trade groups, auto clubs, etc. for use of ETCs for various functions. CDPHE honors requests for building use and/or presentations/tours if they are related to ETC functions and statutory purpose, if it is of educational benefit to the public or repair industry, and if it is not competing with a role best met by the private sector.

ETCs are not available for marketing or endorsement of products, or other such functions where private facilities would be more appropriate. Requests are also not honored for research, development, or evaluation of automotive retrofit (add-on) devices, fuel additives, or other automotive products. The U.S. Environmental Protection Agency (EPA) has an established protocol for the evaluation of such devices and additives. All inquiries in regards to fuel additive/retrofit devices should be made to the EPA.

There are several public- and private-sector trainers in Colorado who conduct nationally-recognized automotive technician training classes for diagnosing and repairing Inspection/Maintenance emissions failures. The ETCs are available for use by these trainers to train automotive technicians. Depending on class size and the individual ETC location, one or two classes may be scheduled per evening. Due to space limitation, no more than two classes will be scheduled per evening per facility.

All scheduling, including training by state employees as part of assigned duties, must be arranged at least one month in advance through the ETC supervisor. A signed application and agreement of ETC use stating the purpose of request, curriculum to be taught, and obligating the trainer to cover loss of tools and/or equipment, building or vehicle damage, re-keying the facility due to lost or non-returned keys, etc. will be required before use of any ETC is allowed. Violation of policies will result in denial of access and billing to the person or his/her company for losses as cited above.

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Motor vehicle emissions resources

Smoking vehicle hotline 

The Smoking Vehicle Hotline helps to identify vehicles with excessive emissions, and gives vehicle owners information that will encourage them to make repairs. 

Report a smoking vehicle
by phone: 303-692-3211         

or email:

Please include the vehicle's license plate number and, if possible, whether it is gasoline- or diesel-powered. We’ll then send a letter to the address that on that vehicle's registration. 

Repairs are required if a vehicle fails a mandatory emissions test because of a visible smoke problem. The cause of such smoke must be corrected before the required emissions sticker can be issued.

Local law enforcement can stop a smoking vehicle, issue a ticket and order the owner to make repairs. Colorado law provides for fines of up to $100 (CRS 42-4-314, 412, 413). Some municipalities may impose additional fines for operating a smoking vehicle.

Engines Off! Idle Reduction Program

School bus drivers, parents, teachers, students and others are turning off their engines whenever parked or stopped for more than one minute. Many fleet drivers also practice this healthy habit.

Idling engines produce thousands of tons of toxic pollution per year in Colorado. Limiting your vehicle’s idling time can dramatically reduce these pollutants and your exposure to them. Engines Off! is designed to reduce toxic vehicle exhaust. 

Please limit your idling whenever possible. It will be good for you, good for your vehicle and good for the air we all breathe!

Engines Off! 

Small Business Technical Assistance Program (SBTAP)

The Small Business Technical Assistance Program (SBTAP) offers technical assistance to the automotive service and repair industry. SBTAP coordinates technician training, provides testing and repair information to technicians, and works to solve vehicle repair issues.

SBTAP is guided by industry experts who serve on a Diagnostic and Repair Advisory Committee. The committee includes representatives of the automotive service and repair industry, tool and equipment manufacturers and automotive training providers. 

Registered repair facilities

SBTAP maintains a network of registered repair facilities in the Denver Metro and North Front Range areas.

Each registered repair facility receives the following from SBTAP:

  • A sign and banner advertising their registered status.

  • A monthly repair effectiveness report card.

  • A quarterly repair newsletter.

  • Specific-vehicle repair-related information that targets "hard-to fix" vehicles.

  • Priority access to their own repair-related Air Care Colorado website.

Registered repair facilities are listed in a guide given to drivers whose vehicles fail an Air Care Colorado emissions test. This guide ranks facilities in order of their Repair Effectiveness Index. You can use the guide to select repair facilities that have a proven record of repairing emissions-related failures. 

Consumer Assistance for Repairs and Service (CARS) program

The CARS program helps reduce emissions from vehicles that fail emissions tests:

  • CARS provides both you and repair facilities with current information on the emissions repair process.
  • CARS investigates and develops solutions to consumer issues and problems within the inspection and repair process.


To learn more about the CARS program, please contact: 

Bill Haan 
Air Care Colorado 


Tampering of emissions control systems is prohibited!

Who is affected by this notice?

Vehicle owners, operators, automotive/diesel technicians and repair facilities, fleet managers, car and truck dealers, and auto/truck parts retailers.

Why is CDPHE issuing this notice?

It is illegal under state and federal law to tamper with the emissions system of any vehicle. All vehicles (gasoline-or-diesel-powered, and light-or-heavy-duty) are subject to the regulation.

What is the definition of tampering?

Tampering is defined as the disconnecting, deactivating, removing or rendering inoperable any emission control device or element of design installed or engineered by the manufacturer on your vehicle, and is prohibited pursuant to CRS 42-4-314.

All vehicles certified for sale in the United States by U.S. EPA or the California Air Resources Board (CARB) have emission control systems that monitor and regulate the engine operations and exhaust gases to maintain air pollutants at strict levels. Tampering with these devices is illegal: it causes excess pollution, and may cause damage to other emissions control devices on your vehicle.

If you remove, disconnect, detach, deactivate, alter, modify, reprogram, or reduce the effectiveness of any emission control device installed by the manufacturer, or use less-effective replacement parts, then you are committing the act of tampering. This includes reprogramming or “re-flashing” the vehicle’s computer, or installing performance chips to circumvent or “defeat” factory settings, or to produce excessive exhaust smoke (diesel trucks). This also includes modifications such as installing an aftermarket exhaust system (pre-catalyst), or installing larger capacity turbocharger and/or turbo waste-gate modifications.

Tampering with a vehicle will also void its warranty.

Any person other than a manufacturer or dealer who violates this section, or any person who violates the Clean Air Act (CAA § 203(a)(3)(B)), shall be subject to a civil penalty of not more than $3,750 per violation. Any manufacturer or dealer who violates this section shall be subject to a civil penalty of not more than $37,500 per violation.

What is CDPHE doing?

CDPHE is reaching out to vehicle owners, fleet managers, vehicle dealers and enforcement agencies to clarify the tampering prohibition. 

What should I do?

Here is a general (but not complete) list of things to check to ensure compliance:

  • Do not remove, disconnect, detach, deactivate, alter, modify, reprogram or in any way render any emission control device or element of design inoperable or less effective than originally designed.
  • Do not sell, lease, or offer for sale or lease any vehicle with a tampered emissions system.
  • Do not purchase a tampered vehicle from any person, dealer, or auto auction.
  • Do not install any non-compliant emission control devices on your vehicle or engine.
  • Use only emissions control systems replacement parts that are approved by U.S. EPA or CARB.

Additional information: 


For additional information on vehicle tampering, contact the CDPHE Emissions Technical Center: 888-861-2646

or email:

Gasoline-powered vehicles:
Randy Bernklau

Diesel-powered vehicles:
Raymond Elick 

Volkswagen Diesel Emissions Settlement

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CDOT Greenhouse Gas Program

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Motor vehicle safety

This is a separate program within CDPHE. 
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Low and Zero Emission Vehicles

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