A smog test only is an emissions inspection without a safety inspection

A smog test only checks whether your vehicle's emissions meet your state's standards. It does not test brakes, lights, tires, steering, or any other safety systems. In states that run both tests, you can often choose to do them separately — the smog test at an emissions station and the safety inspection at a different facility or mechanic. Some states require only the smog test and no safety inspection at all.

The test itself is the same regardless of where you take it. A technician plugs a diagnostic scanner into your vehicle's onboard computer, reads the emissions data, and records whether your vehicle passes or fails the standard for your state and model year. The whole process usually takes 10 to 15 minutes.

Key Takeaways

  • A smog test only measures emissions compliance and does not check brakes, lights, or other safety equipment.
  • You can take a smog test at any Bureau of Automotive Repair (BAR) station in California or at any licensed emissions testing facility in your state.
  • The test costs between $30 and $80 depending on your state and vehicle type, and results are usually available when ready.
  • If your vehicle fails, you must repair the emissions system and retest before you can renew your registration.
  • Some states allow you to delay the smog test until your next registration renewal, while others require it every two years regardless of when you registered.

When your state requires a smog test only

California, Connecticut, Delaware, Maine, Maryland, Massachusetts, Missouri, Nevada, New Jersey, New Mexico, New York, Oregon, Pennsylvania, Rhode Island, Texas, Utah, Vermont, Virginia, Washington, and the District of Columbia all run emissions testing programs. Not all of them require a safety inspection alongside it. California, for example, requires a smog test but no separate safety inspection. Texas requires a smog test in certain counties but not others. New York requires both a smog test and a safety inspection, but you can do them at different places.

Your state's Department of Motor Vehicles or equivalent agency publishes which tests your vehicle needs based on its age, type, and where you live. If you are unsure whether you need a smog test only or a smog test plus safety inspection, call your local DMV office or check your registration renewal notice — it will say what is required.

Where to take a smog test only

In California, you must use a station certified by the Bureau of Automotive Repair. You can search for BAR stations on the California Department of Consumer Affairs website by entering your zip code. In other states, any licensed emissions testing facility can perform the test. Your state's environmental agency or DMV website lists approved stations, or you can search online for "emissions testing near me" plus your state name.

You do not have to go to a dealership. Independent shops, chain service centers, and dedicated emissions testing stations all perform smog tests. Prices vary — expect $30 to $80 depending on your state and whether your vehicle is gasoline, diesel, or hybrid. Some states cap the price; others do not. Call ahead if price matters to you.

What you need to bring and how to prepare

Bring your vehicle registration and a valid photo ID. Some stations also ask for your vehicle identification number (VIN), which is on your registration and on the dashboard at the base of the windshield on the driver's side. You do not need an appointment at most stations, but calling ahead can save you a wait.

Your vehicle's check engine light should not be on. If it is, the station will likely refuse to test you until you have the problem diagnosed and repaired. If your vehicle has been sitting unused for weeks, drive it for at least 10 minutes before the test so the engine reaches normal operating temperature — a cold engine can fail the test even if the emissions system is fine. Do not get an oil change or major service the day of the test; let the vehicle settle for a few days after any work.

What happens if you pass

You receive a certificate or a report number that you present to the DMV when you renew your registration. In some states, the testing station reports the result directly to the DMV electronically, so you do not have to do anything except pay your registration fee. The certificate is usually valid for 30 days, so plan your test timing so that it does not expire before you renew.

Keep the certificate or report number in a safe place. If the DMV does not receive the result and you cannot produce proof, you may not be able to renew your registration until you retest.

What happens if you fail

You receive a failure notice that tells you which emissions system is out of compliance. Common reasons include a faulty oxygen sensor, a clogged catalytic converter, a malfunctioning fuel injector, or a leak in the fuel system. You must take the vehicle to a mechanic, have the problem diagnosed and repaired, and then retest at an emissions station.

Some states allow you to retest at the same station for free or at a reduced price within a set window — usually 30 days. Other states charge full price for the retest. After you pass the retest, you can renew your registration. If you do not retest and pass before your registration expires, your vehicle is no longer legal to drive on public roads.

Repair costs and information programs

Repair costs depend on what failed. A new oxygen sensor might cost $150 to $300 installed. A catalytic converter replacement can run $800 to $2,500 or more. Some states offer repair information programs for low-income vehicle owners who fail the smog test. California's Smog Check Repair information Program, for example, can cover up to $500 of repair costs if you meet income limits. Check your state's environmental agency website or call your local air quality district to ask whether information is available.

If the repair cost exceeds a certain threshold — often 50 percent of your vehicle's current market value — some states allow you to explore for a waiver that lets you renew your registration without passing the test. The rules vary widely. Ask the testing station or your state's environmental agency whether a waiver is possible in your situation.

Timing and registration renewal

When you need a smog test depends on your state and when you registered your vehicle. California requires a smog test every two years, regardless of registration renewal date. Texas requires it only in certain counties and only when you renew your registration. New York requires it every two years. Check your registration renewal notice or your state's DMV website to find out when your test is due.

Plan to take the test at least two weeks before your registration expires, so you have time to retest if you fail. If you take the test too early — more than 30 days before renewal in most states — the result may expire before you can use it, and you will have to test again.

Frequently Asked Questions

Can I take a smog test in a different state than where I registered my vehicle?

No. You must take the test in the state where your vehicle is registered. If you moved to a new state, you need to update your registration in that state first, then take the smog test according to that state's rules and schedule.

What if my vehicle is too old to test?

Most states exempt vehicles older than 30 to 40 years from smog testing. Some states exempt vehicles that are not driven on public roads. Check your state's rules — the DMV website or a call to your local office will tell you whether your vehicle is exempt based on its age and use.

Do I have to pass a smog test to sell my vehicle?

That depends on your state and local rules. Some states require a passing smog test as a condition of sale. Others do not. The buyer may ask for proof of a recent passing test, but it is not always legally required. Check your state's rules before you sell.

Can I do a smog test by mail or online?

No. The test requires a technician to plug a scanner into your vehicle's onboard computer and verify that the vehicle is present and in working condition. You must take the vehicle to a testing station in person.

What if I fail the smog test twice?

You can retest as many times as needed until you pass. Each retest costs the same as the original test. If repair costs are very high, ask the testing station or your state's environmental agency whether you may have access to for a repair information program or a waiver.