Who Needs a Smog Check in Colorado?
Colorado requires smog checks for some vehicles—but not all. If you live or work in the Denver metropolitan area, read this guide to see if you need one.
Written by R.E. Fulton
Reviewed by Kathleen Flear
In
Colorado
, smog checks, or emissions inspections, are required on an annual or biennial basis for most vehicles over seven years old registered in the Denver area and the northern Front Range. Is a smog check required in Colorado?
A smog check is required in Colorado for all vehicles over seven years old registered in Boulder, Broomfield, Denver, Douglas, and Jefferson counties.
Those counties fall within the Automobile Inspection and Readjustment (AIR) Area—a region designated in 1981 as a target for improving air quality and reducing vehicle emissions in the Centennial State. Parts of four other counties fall inside the AIR region:
- Adams County
- Arapahoe County
- Larimer County
- Weld County
For diesel-powered vehicles, smog checks are also required in parts of El Paso County. The requirements for smog checks apply not only to drivers whose cars are registered in the AIR area, but anyone who regularly drives to one of these counties for work. After all, if your vehicle is there five times a week, so are your emissions!
In other words, if you drive a car manufactured before 2015 and live or work in the Denver metropolitan area or the northern Front Range, there’s a good chance that you’re required to get an emissions inspection every one to two years. Your
Colorado vehicle registration
renewal notice will notify you if your vehicle is due for a smog check. RECOMMENDED
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Emissions testing requirements and exemptions
Let’s break the smog check requirements down a little further. If you live or work in the counties listed above, you probably need an inspection—but the schedule, fees, and requirements vary slightly based on the age of your vehicle and the type of
Colorado license plates
it carries. The following vehicles are exempt from Colorado’s smog check requirements:
- Any vehicle less than seven years old
- Vehicles with collector plates manufactured in 1975 or earlier
- All-electric vehicles
- Motorcycles
- Farm vehicles
- Horseless carriages
- Kit cars
- Street rods
If your vehicle doesn’t fit into any of those categories, a smog check is required. Vehicles with standard plates manufactured after 1982 need to pass inspection every two years; vehicles from model years 1976 to 1981 need a check every year. If you have collector plates on a vehicle manufactured between 1976 and 1990, however, your smog check is only required once every five years.
In addition, a smog check is required to
transfer a Colorado title
for any vehicle that's at least seven years old. The responsibility of getting and paying for the test falls on the seller. How to get out of your Colorado smog check: emissions waivers
There’s no way to avoid state emissions testing requirements, but the Colorado Department of Revenue’s Division of Motor Vehicles (DMV) does issue smog check waivers in some circumstances after a failed test. For instance, drivers receiving public assistance may be granted an economic hardship waiver after a failed emissions test.
Gas or diesel emissions waivers are also available in certain cases where the cost of repairs is especially high. For details on those waivers,
head to the DMV’s website
. If you don’t qualify for a waiver, you’ll still have a 30-day grace period. While you can’t get a waiver if your vehicle is temporarily out of state, you can complete an
Application for an Affidavit of Emissions Extension
and send it to the DMV along with proof of insurance, your registration payment, and a VIN verification form or proof of a passing emissions inspection in the county where your car’s currently located. Compare insurance quotes from 50+ insurance companies with Jerry in under 45 seconds
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4.7/5 rating on the App Store | Trusted by 5+ million customers and 7 million cars4.7/5 app rating | Trusted by 5M+ driversWhat is a Colorado vehicle emissions test?
Colorado emissions testing centers perform five different types of smog checks. Depending on the model year and weight of your vehicle, you’ll likely get a combination of these inspections when you bring your vehicle to an Air Care Colorado testing location.
The most basic type of inspection involves a visual check of dashboard lights and your vehicle’s gas cap. The technician will also check that your vehicle’s safe to perform a further inspection on.
For vehicles eight to 11 model years old, the next step is an onboard diagnostics (OBD) scan. This checks for any engine trouble codes associated with your vehicle’s emissions system. The
engine code P0420
, for example, indicates a problem with the catalytic converter
and could cause your vehicle to fail its smog check. Hybrid vehicles are included in this inspection program. If your car is at least 12 years old but was built after 1982, you’ll need an I/M 240 dynamometer test, which is also called a “treadmill test.” Which is exactly what it sounds like: the technician puts the vehicle on a giant treadmill to monitor its operation on the road and test for emissions.
For gasoline vehicles manufactured before 1982 and heavy-duty trucks, the key emissions test is called a “two-speed idle test.” It uses a tachometer and a probe in the exhaust pipe to measure the engine’s speed and emissions. The technician will let the engine idle and rev it alternately in order to get all the necessary readings.
If your vehicle has passed two smog checks in 14 months, you might be eligible for the most convenient type of smog check:
RapidScreen roadside data collection
. Using this method, you just have to drive by a designated emissions-monitoring unit on the side of the highway (typically on an on-ramp). Check Air Care Colorado’s website to see if you’re eligible! What do I need for a smog check in Colorado?
To get a smog check in Colorado, all you need to bring to the testing station is yourself and your vehicle, along with a means of payment. You can find a list of emissions testing locations, along with estimated wait times, on the
Air Care Colorado website
. How much is a smog check in Colorado?
The cost of a smog check in the state of Colorado is either $15 or $25, depending on the age of your vehicle.
For vehicles older than 7 years old manufactured after 1981, the testing fee is $25. For vehicles manufactured in 1981 or earlier, the fee goes down to just $15. You can pay the fee at the vehicle inspection center using cash, a credit or debit card, or a check.
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