Davis County runs one of the stricter vehicle emissions programs in Utah. It is administered by the Davis County Health Department under the name AirCheck Davis, and if your vehicle is more than a few years old, it needs a test every single year. Here is exactly what applies to your vehicle if you live in Layton, Bountiful, Kaysville, Farmington, or anywhere else in the county.
The schedule: every year after six
The rule that matters most for Davis drivers: once a vehicle is six or more model years old, it needs an emissions test every year before you can renew its registration. In 2026 that covers every vehicle from model year 1996 through 2020.
Newer vehicles get a break. In their first two model years they are exempt. After that, until they turn six, they test every other year on an even/odd schedule: even model years in even calendar years and odd model years in odd years.
| Model year (2026) | Test required in 2026? |
|---|---|
| 2025 to 2026 | No, too new |
| 2024, 2022 | Yes (even model year, even calendar year) |
| 2023, 2021 | No, due in 2027 |
| 1996 to 2020 | Yes, every year |
| 1995 and older | No, no longer tested |
That is a big difference from Cache County, where no vehicle tests more often than every other year and new vehicles skip their first six years entirely. Our county comparison guide lays out all five testing counties side by side.
Which vehicles are tested
- Gasoline and alternative-fuel vehicles: 1996 and newer up to 8,500 pounds GVWR, and 2008 and newer from 8,501 to 14,000 pounds
- Diesel vehicles: 1998 and newer up to 14,000 pounds GVWR
Heavy-duty diesels over 14,000 pounds, diesels from 1997 and older, fully electric vehicles, and qualifying farm trucks are exempt.
Older vehicles: no longer tested
Vehicles from model year 1995 and older were tested with a two-speed idle tailpipe test, since they do not have the OBD-II diagnostic port that newer cars use. Davis County ended that test on October 1, 2026, so those vehicles no longer need an emissions test. Some older county web pages still mention testing back to 1968; the October 2026 change replaces that.
You need a Davis certificate even if you register elsewhere
Davis County ties the requirement to where you live, not just where the car is registered. If your primary residence is in Davis County, you need a valid emissions certificate or waiver to register a vehicle in any Utah county. Registering at a relative's address in a county without testing does not get around it.
Timing it with your registration
Your emissions test must be done within two months before your registration renewal. Results go to the Utah DMV electronically, so once you pass you can renew online right away. With yearly testing, it is worth signing up for a free registration reminder so the deadline never sneaks up on you. Our registration renewal guide walks through the whole process.
If your vehicle fails
Most failures come down to a check engine light or emissions monitors that are not ready after a battery change or cleared codes. Our guide on what to do when a vehicle fails covers the fixes. If repairs get expensive, the Davis County Health Department can grant a one-year waiver when you show qualifying emissions repairs made within 60 days before the failed test. For 1996 and newer vehicles the minimum repair spending is $450. Vehicles with missing emissions equipment, catalyst monitors that are not ready, or a prior waiver do not qualify.
Getting tested without leaving home
Yearly testing is exactly where a mobile test pays off. Instead of a trip to a station every year, a certified technician comes to your driveway or workplace anywhere in Davis County, including Layton, Bountiful, Kaysville, Farmington, and Clearfield. The OBD-II test takes about 15 minutes, costs $49.99 with a free retest included, and the results go straight to the DMV. Davis County service launches in November 2026.
Common Questions
Every year once your vehicle is 6 or more model years old. Newer vehicles test every other year: even model years in even calendar years and odd model years in odd years. The first two model years are exempt.
Gasoline and alternative-fuel vehicles from 1996 and newer up to 8,500 pounds GVWR, 2008 and newer gasoline vehicles from 8,501 to 14,000 pounds, and diesel vehicles from 1998 and newer up to 14,000 pounds. Heavy-duty diesels over 14,000 pounds and diesels from 1997 and older are exempt.
Yes. As of October 1, 2026, Davis County no longer tests vehicles from model year 1995 and older. It ended the two-speed idle (tailpipe) test those vehicles used, so only 1996 and newer vehicles are tested now.
Yes. Davis County requires anyone whose primary residence is in Davis County to provide a valid emissions certificate or waiver to register a vehicle, no matter which Utah county it is registered in.
Possibly. The Davis County Health Department grants a one-year waiver if you can show qualifying emissions repairs done within 60 days before a failed test. For 1996 and newer vehicles the minimum repair spending is $450. Vehicles with missing emissions equipment, catalyst monitors that are not ready, or a prior waiver do not qualify.