The Colorado Emissions Test Guide for Frederick Drivers
Fees and rules updated October 2026
You pass the Colorado emissions test when the check engine light is off, the gas cap seals, the readiness monitors read Ready and nothing smokes. Most failures in a newer car come from one of those four, not from the tailpipe numbers. Frederick sits inside the test area, so a gas car past its seventh model year needs the $35 test every two years. We wrote this so you can sort out the easy fails at home before you sit in the Dacono line.
Need to Know Now
- Gas cars skip the test for seven model years, then test every two years.
- The test costs $35. Cars from 1981 and older pay $20 and test every year.
- A lit check engine light or a bad gas cap fails the car.
- A new battery or cleared codes can set monitors to Not Ready.
- The closest Air Care station is 5222 Silver Peak Ave. in Dacono.
- After $715 in emissions repairs, a car that still fails can apply for a waiver.
Does Your Car Need the Test
Look at the registration renewal card from Weld County first. It will say EMISSIONS TEST REQUIRED, PASSED ROADSIDE EMISSIONS or NO EMISSIONS TEST REQUIRED. Air Care Colorado says that card is the place to start.
The test area covers Adams, Arapahoe, Boulder, Broomfield, Denver, Douglas, Jefferson, Larimer and Weld counties. Only part of Weld is in it. The state map that Weld County links to draws the line around the south west corner of the county. Frederick, Firestone, Dacono, Mead and Fort Lupton sit inside it. Platteville sits just east of the line. The map itself says the county clerk has the final word on any one address.
Live outside the area but drive in 90 days a year for work or school? Air Care says you may need the test anyway.
| Gas car model year | What the DMV asks in 2026 |
|---|---|
| 2021 to 2026 | No test |
| 2020 | No test to renew. A test when it is sold. |
| 1982 to 2019 | A test every two years, $35 |
| 1981 and older | A test every year, $20 |
| All electric, motorcycle, kit car | No test |
A test for a 1982 or newer car is good for 24 months, per the Colorado General Assembly. Diesels follow their own program. Air Care stations do not test diesels at all.
What Fails a Car
Air Care lists the usual reasons a car fails. Emissions over the limit. Problems the computer found. A warning light still on during the test. Emissions parts or the gas cap missing or not working. Smoke you can see.
How your car gets tested depends on its age. Air Care uses three tests.
| Age of the car | The test | What trips it |
|---|---|---|
| 8 to 11 model years old | OBD plug in test, no driving | Check engine light, stored codes, monitors not ready |
| 12 model years old back to 1982 | IM240 treadmill, about four minutes of driving | Tailpipe numbers under load, plus the gas cap |
| 1981 and older | Two speed idle test | Tailpipe numbers at idle |
The gas cap gets its own test. Air Care says a missing or leaking cap fails the car. You then need a full retest with the new cap on, not only a cap check.
Wide wheels change where you go. A front or all wheel drive car on low profile rims of 17 inches or more needs a special treadmill. Air Care says only Sheridan, Boulder, Ken Caryl and Fort Collins have one. Dacono and Longmont do not.
The Battery Trap
Your car runs a set of self checks called readiness monitors. Air Care says some cars have as many as 11. Each one has to finish and read Ready before the plug in test can grade the car.
Those checks wipe when the battery goes dead, gets unhooked or gets replaced. They also wipe when someone clears codes with a scan tool. The Texas Department of Public Safety calls a disconnected battery the most common reason monitors read Not Ready.
This bites people here every fall. The first cold snap kills a tired battery. A new one goes in. A week later the renewal card shows up and the car goes straight to the test. It gets turned away for monitors that have not run yet.
The fix is driving, not parts. Monitors reset under certain driving conditions, and Air Care says some makers publish the exact steps. Plan on normal town and highway driving for a few days after the battery work. A mechanic with a scan tool can tell you which monitors are still not done before you make the trip.
A Driveway Check Before the Test
- Look at the dash with the engine running. The check engine light should come on with the key and then go out. If it stays on, fix the cause first.
- Check the gas cap. Look at the rubber seal for cracks. Turn it until it clicks. A loose cap can set a code on its own.
- Think about the last month. New battery? Jump start after it went flat? Codes cleared? Then drive it for several days before the test.
- Watch the tailpipe on a cold start. Blue smoke means oil. Visible smoke fails the car, and no waiver covers it.
- Warm it up. Drive it a while on the way in so the engine is at full heat when it rolls onto the treadmill.
- Pick your time. Air Care says the middle two weeks of the month, late afternoons and Saturdays are best. Skip Mondays, the last days of the month and the day after a holiday.
You do not need to bring paperwork. Air Care says you only need to bring the car. Most tests finish in under 20 minutes from the time you pull in. Stations are open weekdays and Saturday mornings until 1 p.m., and closed Sundays.
Common Misreads
The test is $25. Older guides and the state map still say so. Air Care and the DMV both list $35 now for 1982 and newer cars. Douglas County says the $35 fee started with renewals in March 2026.
Cars under four years old skip it. That number is for diesels. A gas car skips the test for its first seven model years.
Clear the code and go test. This backfires. Clearing the code also resets the monitors. The light is off, but the car is not ready to be graded. If the fault is real, the light comes back anyway.
Hybrids are exempt. Not all of them. The Colorado General Assembly table lists hybrids of model year 2010 or older as tested every two years. Only cars with no gas tank and no tailpipe are fully exempt.
A used car comes with a free pass. The seller owes you a passing test that has not been used for a registration. Buy from a dealer and the car fails? Air Care says you have five business days to take it back for repair or a buyback.
When the Car Fails
Air Care says the fix can be as simple as an oil change. It can also be an oxygen sensor, a catalytic converter or a part the computer controls. The fail report names the area that failed. Bring it to whoever does the repair.
If the repair does not get you there, the state has a backstop. The DMV waiver sheet sets these lines.
| Waiver | What it takes |
|---|---|
| Repair waiver, 1968 and newer gas car | $715 spent on emissions repairs and it still fails |
| Repair waiver, 1967 and older gas car | $75 spent on emissions repairs |
| Economic hardship, gas cars only | Public assistance, and the car is your only ride. Once per car. |
| Repair waiver, light diesel | $750 spent on emissions repairs |
No waiver covers smoke, missing or tampered parts or a failed gas cap. The DMV also says only labor billed by a professional mechanic counts toward the repair amount. Spent less than the line and still failing? The state runs free Emissions Technical Centers that look at cars after a failed retest.
We would rather you find a lit light in your driveway than in the Dacono lane. Joe reads the live data while the engine runs, not only the stored code. Text a photo of the dash and the code if you have it to (303) 521-6301.
What Comes Up on Calls
Where do I get an emissions test near Frederick?
The Air Care Colorado station at 5222 Silver Peak Ave. in Dacono is the closest. Longmont has one at 4040 Rogers Rd. No appointment is needed.
How much is an emissions test in Colorado?
$35 for 1982 and newer gas cars. $20 for 1981 and older. Air Care takes cash, checks and cards, with a 2% fee on cards.
Will my car pass with the check engine light on?
No. Air Care lists a warning light that stays on during the test as a fail. Find and fix the cause, then drive a few days so the monitors reset.
Can I skip the emissions test in Colorado?
Sometimes. RapidScreen roadside units read cars as they drive past. Two clean readings in the 14 months before your renewal, and at least 60 days ahead of it, let you skip the station.
What do I need to bring to my emissions test?
Only the car. Air Care says no paperwork is needed at the station.
See more Joe-lopy's in Google. Make us a preferred source →Info Sources
| What we cited | Where it came from |
|---|---|
| Fees, hours, best times, dealer rule | Air Care Colorado, Need to Know |
| Counties, fail reasons, monitors, gas cap | Air Care Colorado, FAQ |
| Test by age, wide wheel stations | Air Care Colorado, Where to Go |
| Dacono and Longmont station addresses | Air Care Colorado, Wait Times |
| RapidScreen rules | Air Care Colorado, RapidScreen |
| Model year table and fees | Colorado DMV, Gas Emissions Requirements |
| Waiver rules, seller rule, mechanic labor | Colorado DMV, Emissions |
| Waiver amounts | Colorado DMV, My Vehicle Failed Emissions |
| 24 month test, hybrids | Colorado General Assembly, Emissions |
| Weld County test area map | Weld County, Emissions Testing |
| $35 fee from March 2026 | Douglas County, Vehicle Emissions Information |
| Battery as the top cause of Not Ready | Texas DPS, Ready or Not |