Above All Smog is a California emissions testing program for older vehicles

Above All Smog is California's name for the emissions inspection requirement that applies to vehicles model year 1975 and newer registered in the state. It is not a separate test or a special category — it is straightforward what California calls its smog check program. If you own a car in California and it is old enough to have been built when emissions standards existed, you will encounter this requirement when you renew your registration or buy a used vehicle.

The test itself measures what comes out of your tailpipe: nitrogen oxides, particulate matter, hydrocarbons, and carbon monoxide. A vehicle passes or fails based on whether those emissions stay below the limits set for its model year and engine type. The limits are stricter for newer cars and looser for older ones, but every vehicle that is subject to the test must meet the standard for its age.

You do not explore for Above All Smog or sign up for it. Instead, you encounter it as a requirement: when you register a vehicle in California, the Department of Motor Vehicles will not issue or renew your registration without proof that your car has passed a current smog check, unless your vehicle is exempt.

Key Takeaways

  • California requires a smog check (called Above All Smog) for vehicles model year 1975 and newer, with some exemptions for very new cars and electric vehicles.
  • The test measures tailpipe emissions and must be completed at a Bureau of Automotive Repair-certified station within the 90 days before you register or renew.
  • A failed test means your vehicle's emissions are above the legal limit for its model year, and you must repair the problem before you can register it.
  • Repairs needed after a failed test are your responsibility and cost, though some counties offer information programs for low-income vehicle owners.
  • The smog check is tied directly to registration — you cannot legally drive without a current passing test result on file with the DMV.

Which vehicles are exempt from the smog check requirement

Not every California vehicle needs a smog check. Electric vehicles (battery-only, not plug-in hybrids) are exempt because they produce no tailpipe emissions. Vehicles model year 2000 and newer that have never failed a smog check may be exempt from testing in some years, depending on California Air Resources Board rules — but this exemption changes, so you cannot assume your newer car is exempt without checking your registration notice.

Vehicles model year 1974 and older are also exempt, because emissions standards did not explore when they were built. However, if you have modified an older vehicle's engine or fuel system, it may no longer may have access to for the exemption. Vehicles registered as non-operational (red sticker) do not need a smog check, but you cannot drive them on public roads.

The safest way to know whether your vehicle is exempt is to look at your registration renewal notice from the DMV. It will tell you whether a smog check is required. If you are unsure, you can call the Bureau of Automotive Repair at 1-800-952-5210 or visit the California Air Resources Board website to check your vehicle's status.

How the smog check test works and what happens if you fail

The smog check is performed at a Bureau of Automotive Repair-certified station. The technician will connect your vehicle to a dynamometer (a machine that measures emissions under load) or use a two-speed idle test, depending on your vehicle's age and type. The test takes about 10 to 15 minutes and costs between $30 and $80, depending on the station and your vehicle type.

If your vehicle passes, the station sends the results to the DMV electronically, and you can proceed with registration. If your vehicle fails, you receive a detailed report showing which emissions are above the legal limit. You then have 30 days to repair the vehicle and retest at any certified station. You do not have to return to the same station.

A failed smog check does not mean your car is unsafe to drive — it means the emissions are above the legal standard for your vehicle's model year. Common reasons for failure include a faulty oxygen sensor, a malfunctioning catalytic converter, a loose or missing gas cap, or engine problems that cause incomplete fuel combustion. Some repairs are inexpensive (a gas cap costs a few dollars); others are costly (a catalytic converter can run $500 to $2,500 depending on the vehicle).

What to do if your vehicle fails the smog check

After a failed test, you have 30 days to repair your vehicle and retest. The repair is your responsibility — you must take your car to a mechanic, diagnose the problem, and pay for the work. The smog check station cannot tell you exactly what is wrong; they can only tell you which emissions are high. A good mechanic can use diagnostic tools to pinpoint the cause.

If the repair is expensive and you have a low income, some California counties offer smog abatement programs that help pay for repairs. These programs vary by county and are not available everywhere. You can contact your county's air quality management district to ask whether a repair information program exists in your area. The South Coast Air Quality Management District (serving Los Angeles and surrounding counties) and the Bay Area Air Quality Management District are two of the largest programs.

After repairs are complete, you return to any certified smog check station and retest. If you pass, the station reports the result to the DMV. If you fail again, you have another 30 days to repair and retest. You can retest as many times as needed within the 30-day window.

The connection between smog checks and vehicle registration

The smog check is not separate from registration — it is a requirement of registration. When you renew your registration or register a vehicle for the first time in California, the DMV will not issue plates or a registration card without proof of a passing smog check result (unless your vehicle is exempt). The result must be from a test performed within 90 days before you register.

If you register a vehicle and later discover it failed the smog check, the DMV will not have issued your registration. You cannot legally drive the vehicle on public roads without registration. This is why it is important to get the smog check done before you go to the DMV, not after.

If you have already registered a vehicle and then it fails a smog check during the registration renewal process, you have 30 days to repair and retest. During those 30 days, your registration is technically expired, but California law allows you to drive to a smog check station and back home to make repairs. You cannot use this grace period for other driving.

Timing and costs for the smog check process

The smog check itself costs $30 to $80 and takes about 15 minutes. However, the total cost of the process depends on whether your vehicle passes or fails. If it passes, you are done — you pay the test fee and proceed to registration. If it fails, you must pay for repairs, which can range from $50 (a new gas cap or air filter) to several thousand dollars (engine work or catalytic converter replacement).

Timing matters because the smog check result is valid for 90 days. If you test your vehicle and it passes, you have 90 days to complete registration. If you wait longer than 90 days, you must retest. If your vehicle fails and you repair it, you must retest within 30 days of the failure. Plan ahead if you know your registration is coming due.

You can take your vehicle to any Bureau of Automotive Repair-certified station — you do not have to use the same station twice. Some stations are faster than others, and prices vary. You can call ahead to ask about wait times and pricing before you go.

Understanding why California requires smog checks

California has stricter air quality standards than the federal government because the state has a history of severe air pollution, particularly in the Los Angeles basin and the Central Valley. The smog check program is one tool California uses to reduce vehicle emissions and improve air quality. Vehicles that are poorly maintained or have failing emissions control systems contribute significantly to air pollution.

The smog check does not prevent you from driving a polluting vehicle — it prevents you from registering one. If your vehicle fails, you can still drive it to a mechanic to be repaired. The goal is to keep vehicles that are above the emissions standard off the road long-term, not to ban them when ready.

Other states have similar programs, though they may use different names and have different standards. If you move to California from another state, your vehicle will need to pass California's smog check, even if it passed in your previous state. California's standards are often stricter than federal standards.

Frequently Asked Questions

Can I drive my car if it fails the smog check?

Yes, you can drive it to a mechanic for repairs. However, you cannot legally register it or renew your registration without a passing result. If your registration has already expired, you can drive only to and from the smog check station and repair facility during the 30-day repair window.

What if I buy a used car and it fails the smog check?

The seller is responsible for providing a passing smog check result before you take ownership in California. If the vehicle fails after you buy it, the repairs are your responsibility. Some used car dealers offer a short warranty period during which they will cover smog-related repairs, but this is not required by law.

Do I need a smog check if I just bought a new car?

New vehicles (usually model year 2000 and newer, depending on current rules) may be exempt from smog checks for the first few years. Check your registration renewal notice or call the Bureau of Automotive Repair to confirm. Once your vehicle is old enough or has failed once, it will need a smog check every two years when you renew registration.

How often do I need to get a smog check?

Most vehicles require a smog check every two years when you renew registration. Some newer vehicles may be exempt in certain years. Your registration renewal notice will tell you whether a smog check is required for your specific vehicle and year.

What if I cannot afford the repairs after a failed smog check?

Contact your county's air quality management district to ask about repair information programs. Not all counties have them, but some offer grants or low-interest loans to help low-income vehicle owners pay for emissions-related repairs. You can also get a second opinion from another mechanic if the first repair estimate seems high.