Make sure your vehicle does not smoke. Visible smoke is a sure sign of excess pollution and will cause your vehicle to fail the test.
Don't overfill your gas tank. When filling your tank, resist the impulse to get just a little bit more into the tank after the nozzle clicks off. This excess gasoline has nowhere to expand so it saturates a part of the emissions control system resulting in increased emissions.
Follow recommended maintenance schedules for your vehicle. Read your owner's manual, and follow maintenance guidelines. Your vehicle will perform more efficiently.
Fully warm up your vehicle before testing. Until your vehicle is at normal operating temperature, it emits excess pollution. Run your vehicle at highway speed for at least 15 minutes prior to undergoing an emissions test. Limit use of air conditioning and defroster if possible.
Make sure your brakes are in good condition. Poor brakes can make the vehicle difficult to test on the dynamometer, and may cause the vehicle to be rejected from testing.
Make sure your tires are properly inflated. Tires that are unevenly inflated, under-inflated or mismatched make the vehicle difficult to test on the dynamometer, and may cause the vehicle to be rejected from testing.
Your vehicle's emissions control equipment must be intact and functioning. Missing or tampered emissions control equipment will cause your vehicle to fail the test.
Check to see you have a gas cap in place. This is required equipment. It must be the correct type for your vehicle, and it must have a tight seal. A missing or leaky gas cap will cause your vehicle to fail the test.
Ensure the integrity of your exhaust system. Excessive exhaust leaks can cause your vehicle to be rejected from testing. Exhaust leaks are also dangerous to the vehicle's occupants.
Front-wheel drive vehicles: Make sure the front suspension is properly aligned. Poor front-end alignment will make the vehicle difficult to test on the dynamometer, and may cause the vehicle to be rejected from testing.

Quick Consumer Information
Hours of Operation:
Monday to Friday, 8 a.m. to 5:30 p.m. and Saturdays, 8 a.m. to 1 p.m.
Closed Sundays and state holidays.
Q. |
Do you need a test? |
A. |
Make sure you need a test before you present your vehicle for testing! State regulation requires testing centers to test all vehicles that are presented for testing. Emissions inspectors are prohibited from making a judgment on whether your vehicle really needs a test. No refunds can be given for emissions tests on vehicles that were not actually due for a test. If you are not sure, call the Air Care Colorado Hotline at 303-456-7090, or your county motor vehicle office to ask. Effective July 1, 2001, window stickers were eliminated by state law.
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Q. |
Cost? |
A. |
1982 and newer vehicles require an enhanced emissions test every two years at a cost of $25.
1981 and older vehicles require a two-speed idle test every year at a cost of $15.00. Vehicle Identification Number (VIN) verifications are also available at a cost of $20.00. Payment for the test may be made by cash or check. (Please make checks payable to: ACC.) Please Note: We cannot accept "temporary" checks, i.e., checks without printed identification. |
Q. |
Grace period? |
A. |
There is a 30-day grace period for your annual or biennial emissions test expiration. However, keep in mind that more than 30 days over the expiration could cost you a $50 ticket. To request an extension, please visit your Motor Vehicle office.
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Q. |
Free Retest? |
A. |
If your vehicle fails the emissions test, the first retest is free within ten calendar days (not ten business days). If the 10th calendar day falls on a Sunday or holiday when the stations are closed, the free retest will be extended to the 11th day.
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Q. |
Best Times to Test? |
A. |
Avoid waiting in line. Come on Saturdays, early mornings, and during the middle two weeks of the month.
High volume times to avoid are Mondays, the lunch hour, the first business day after any holiday, and the first few and last few days of the month. |
Q. |
Tire Sizes and Dynamometers? |
A. |
Front wheel and all wheel drive vehicles with low profile tire sizes 17 inches or larger in diameter, or vehicles with tire sizes larger than 34 inches cannot be safely tested on the dynamometer.
Only vehicles with manufacturer-equipped undersized or oversized tires that do not fit safely on the dynamometer will be authorized by the state to undergo an idle test instead of a dynamometer test. Vehicles with tires larger or smaller than original equipment that do not fit safely on the dynamometer must be returned to stock condition for testing. Vehicles with non-original undersized or oversized tires will not receive authorization from the state for an idle test. |
Q. |
VIN Verifications? |
A. |
If your vehicle has not been registered within the state of Colorado in the past, in addition to an emissions test, you must also obtain a Vehicle Identification Number (VIN) verification prior to registering your vehicle. VIN Verifications may be obtained at an Air Care Colorado test center; however, they are not performed in the test lanes. They must be requested at the station office. Fee is $20.
Brand New Vehicles If you are bringing into the program area a brand new vehicle that has never been registered in any state, you do not need an emissions test. If the vehicle has never before been registered anywhere in the state of Colorado, you will need a VIN verification. Do not drive the vehicle into the testing lanes for a VIN verification; request a VIN verification at the office. The following provide VIN verifications:
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