Emissions Testing (Smog Checks) — National Guide
Many states require periodic emissions testing before you can register or renew your vehicle. Use this guide to understand what’s tested, how much it typically costs, testing intervals, exemptions, and how to prepare. Select your state to see exact rules, approved stations, and any county-specific requirements.
Get Your Emissions Test Done in 4 Steps:
- Check if your vehicle and county require testing (most states target OBD-II model years 1996+).
- Choose a certified station or state inspection lane (walk-in or appointment).
- Bring your registration/renewal notice, payment, and ID; complete the test (10–20 minutes).
- Receive a pass (electronic or paper) or a fail with repair advice; complete registration or renew online if eligible.
Eligibility
- Most programs target gasoline vehicles model year 1996 and newer registered in designated counties/air quality areas.
- Older vehicles (pre-1996), heavy-duty, or diesel vehicles may follow different tests or be exempt depending on state and weight class.
- Brand-new vehicles are commonly exempt for the first 2–5 model years, depending on state.
- Classic/antique, fully electric, or hybrid vehicles may have exemptions or modified requirements depending on state law.
- Fleet, government, and commercial vehicles may have separate schedules or opacity standards.
Documents
- Vehicle Registration or Renewal Notice
- Payment Method
- Valid Photo ID
- Repair Invoices (for Retests/waivers)
Emissions Testing Fees & Costs
- Fee — $15–$40 OBD-II emissions test (1996+ gasoline vehicles)
- Fee — $25–$50 Tailpipe/ASM or IM240 test (older vehicles)
- Fee — $25–$60 Diesel opacity test (where required)
- Fee — $0–$25 Retest fee (within 30–60 days after fail, many states discount or waive if repaired)
- Fee — $0–$20 Waiver application (if offered by state)
FAQ
How often do I need an emissions test?
Most programs require testing every 1–2 years, aligned with your registration cycle. Some states test only in specific counties or ozone nonattainment areas, while rural counties are exempt. New vehicles often skip the first 2–5 years.
What vehicles are tested and how?
1996+ gasoline vehicles usually receive an OBD-II scan to check emission monitors and trouble codes. Older vehicles may get a tailpipe dynamometer or idle test. Diesel vehicles often undergo an opacity or OBD/visual inspection depending on weight and model year.
What if my car fails the test?
You’ll receive diagnostic information and a list of areas to repair. After fixing issues, return for a retest—often free or discounted within 30–60 days. If repairs exceed a set amount, many states offer a hardship or cost-waiver with proper documentation.
Can I renew registration online after passing?
In many states, stations submit results electronically. Once your pass posts to the system, you can renew online immediately. If your state requires a paper certificate, keep it for your records and follow the renewal instructions on your notice.
How much does emissions testing cost?
Expect $15–$50 depending on state, test type, and station. OBD-only tests are usually on the lower end, while tailpipe or diesel opacity tests may cost more. Retests are commonly $0–$25 within a set timeframe.
State contact
Phone: (800) 777-0133
Hours: Monday-Friday 8:00 AM - 5:00 PM
Official site