Smog Check Frequently Asked Questions
What is the Smog Check Program?
The Smog Check Program is a vehicle inspection and maintenance program administered by the Bureau of Automotive Repair (BAR). The program is designed to improve air quality by identifying vehicles with excess emissions so they can be properly repaired or retired. Since its implementation in 1984, the program has greatly reduced air pollution created by millions of vehicles in California.
What is a Smog Check?
A Smog Check is an inspection of a vehicle’s emissions-control equipment and systems to measure the amount and type of pollutants the vehicle is emitting. A Smog Check may include any of the following inspections, depending on the vehicle type and model year:
- Visual inspection of emissions-control equipment and systems.
- Functional inspection of the vehicle’s check engine light, ignition timing, exhaust gas recirculation system, fuel evaporative system, and gas cap.
- Functional inspection of the vehicle’s on-board diagnostic (OBD) system.
- Tailpipe emissions inspection.
When is a Smog Check required?
A Smog Check is required every other year (biennially) as part of the vehicle registration process. The Department of Motor Vehicles (DMV) registration renewal notice will indicate if a Smog Check is required. A Smog Check is also required when a vehicle changes ownership or when it is registered for the first time in California.
Vehicles Subject to Smog Check
What vehicles require a Smog Check?
Gasoline-powered vehicles, hybrid vehicles, and alternative-fuel vehicles that are model-year 1976 and newer require a Smog Check, with the following exceptions:
- Eight model years and newer do not require a biennial Smog Check.
- Four model years and newer do not require a change-of-ownership Smog Check.
To determine the first year a vehicle requires a biennial or change-of-ownership Smog Check, add eight or four, respectively, to the model year of a vehicle.
For example, a 2020 model-year vehicle will first be subject to a biennial Smog Check in 2028 (2020 + 8 = 2028). That same vehicle will require a change-of-ownership Smog Check if sold in or after 2024 (2020 + 4 = 2024).
Diesel-powered vehicles that are model-year 1998 and newer with a gross vehicle weight rating of 14,000 pounds and less require a Smog Check. There are no model year exceptions for diesel-powered vehicles.
What vehicles do not require a Smog Check?
- Gasoline-powered vehicles, hybrid vehicles, and alternative-fuel vehicles that are model-year 1975 and older.
- Gasoline-powered vehicles, hybrid vehicles, and alternative-fuel vehicles that are eight model years and newer do not require a biennial Smog Check.
- Gasoline-powered vehicles, hybrid vehicles, and alternative-fuel vehicles that are four model years and newer do not require a change-of-ownership Smog Check.
- Diesel-powered vehicles that are model-year 1997 and older.
- Diesel-powered vehicles with a gross vehicle weight rating of more than 14,000 pounds.
- Electric-powered vehicles.
My 1976 model-year vehicle was built in 1975. Does it require a Smog Check?
Yes. Smog Check requirements are based on vehicle type and model year, not the date of manufacture.
My vehicle is eight years old. Why does it require a Smog Check?
Smog Check requirements are based on vehicle type and model year. Model years are released in the calendar year prior to a vehicle’s model year. Thus, a vehicle is one model year old when the model year matches the calendar year. For example, a 2010 model-year vehicle is one model year old in 2010 and nine model years old in 2018. Accordingly, a 2010 model-year vehicle requires its first biennial Smog Check in 2018.
Does my collector car require a Smog Check?
Collector cars that are model-year 1976 and newer require a Smog Check. Because Smog Check stations do not have the equipment necessary to inspect collector cars, collector cars are eligible for an abbreviated inspection performed by a Smog Check Referee. For more information, visit our Collector Car page or asktheref.org.
All vehicles that are model-year 1975 and older do not require a Smog Check.
Do government-owned vehicles require a Smog Check?
Yes. Passenger vehicles or light-duty trucks owned or leased by federal, state, county, city, and special district agencies require a Smog Check.
Preparing for a Smog Check
Where do I take my vehicle for a Smog Check?
BAR licenses several different types of Smog Check stations to perform Smog Check Program services and meet the needs of consumers and their vehicles:
- Test-and-repair stations are licensed to perform Smog Checks and emission-related repairs on vehicles.
- Test-only stations are licensed to only perform Smog Checks. These stations are not authorized to diagnose the reasons for a Smog Check failure or perform emission-related repairs on vehicles.
- Repair only stations are licensed to diagnose and perform emissions-related repairs on vehicles. These stations are not authorized to perform Smog Checks.
- STAR stations are test-and-repair stations or test-only stations that meet performance standards established by BAR. Your DMV registration renewal notice will indicate whether your vehicle requires a Smog Check at a STAR station.
Stations are required to post a sign indicating the services it is licensed to perform.
How can I find a Smog Check station?
Use BAR’s Auto Shop Locator to find a station near you.
Do I need to take anything with me to the Smog Check station?
If your DMV vehicle registration renewal notice indicates a Smog Check is required, remember to take the notice with you. This will help ensure that the correct vehicle information and Smog Check certificate are electronically sent to DMV.
How can I help my vehicle pass a Smog Check?
Performing regular maintenance according to your owner’s manual and not tampering with the emissions-control equipment will help improve your vehicle’s chances of passing a Smog Check. If the "check engine" light comes on, get your vehicle repaired as soon as possible—do not wait for the vehicle’s next scheduled Smog Check. A blinking or flashing light indicates a malfunction that should be addressed immediately to avoid serious damage to the vehicle. Check your owner’s manual for any parts or repairs that may be covered under your vehicle manufacturer’s emissions warranty.
What is a pretest?
A pretest, or pre-inspection, is an unofficial test performed by a station to help identify emissions-related problems prior to an official Smog Check. Following a pretest, the station will provide a vehicle inspection report showing the vehicle’s results; however, a smog certificate will not be issued. Stations may charge for this service and must obtain consumer authorization before performing the pretest.
How much does a Smog Check cost?
BAR does not regulate prices, but recommends that you shop around and compare prices at several different stations before taking your vehicle in for its Smog Check. Stations are required to post a list of prices charged for the services it is licensed to perform.
Smog Check Results
What happens if my vehicle passes the Smog Check?
If your vehicle passes, the station will provide you a vehicle inspection report showing your vehicle’s results and will electronically send the smog certificate to DMV. The smog certificate is valid for 90 days.
What resources are available if my vehicle fails the Smog Check?
If your vehicle fails, the station will provide you a vehicle inspection report that shows your vehicle’s results and the reason(s) your vehicle did not pass. If you have questions, ask the station to explain the information on the report.
To address the reason(s) for the failure, you may:
- Complete the emissions-related repairs – Any needed repairs should be performed by a station licensed to perform Smog Check repairs. After completing the repairs, have your vehicle reinspected. The station will provide you a final vehicle inspection report once your vehicle passes Smog Check and will electronically send the certificate to DMV.
- Visit a Smog Check Referee – Referees offer a second opinion on Smog Check results and can assist you with inspections of unusual vehicles and locating hard-to-find emissions parts. To learn more or to schedule an appointment, visit www.asktheref.org.
- Apply to the Consumer Assistance Program – The Consumer Assistance Program offers income-eligible consumers assistance toward emissions-related repairs at a STAR test-and-repair station if their vehicle fails its biennial Smog Check inspection. The program also offers eligible consumers an incentive to retire their operational vehicle at a BAR-contracted dismantler site. To review eligibility requirements and apply, visit the Consumer Assistance Program page.
My vehicle failed a Smog Check for having modified software. What can I do?
Beginning July 19, 2021, vehicles with software not provided by the original equipment manufacturer (OEM) or approved through a California Air Resources Board (CARB) Executive Order (EO) will fail Smog Check.
Before your vehicle will pass a Smog Check, you must have the vehicle’s software restored to the OEM or EO approved software version. Once the software is restored, have your vehicle reinspected by a licensed Smog Check station. Note that vehicles initially directed to a STAR or Referee station must return to the same station type to complete the inspection process.
If you believe the vehicle’s software is already OEM or CARB-approved and yet your vehicle failed Smog Check, schedule an inspection with the Smog Check Referee. If you unknowingly purchased a vehicle with illegally-modified software, you may file a complaint with BAR.
Learn more about modified software checks.
My vehicle’s readiness monitors are "incomplete" or "not ready." What can I do?
Modern vehicles are equipped with on-board diagnostic (OBD) computer systems that perform self-diagnostic tests. The tests are performed during normal vehicle operation to ensure the vehicle’s emissions-control equipment is functioning properly. Individual "readiness monitors" or "readiness indicators" are set to "ready" after each test is completed. A vehicle cannot pass a Smog Check until the required self-diagnostic tests are complete and the readiness monitors are ready.
For most vehicles, readiness monitors will set during normal operation and do not require any special attention prior to a Smog Check. However, if your vehicle has had recent repairs or had its battery disconnected, the readiness monitors may be cleared and need to reset. Drive the vehicle for a week or two to allow the OBD system time to set the readiness monitors before taking your vehicle for a Smog Check.
In some cases, vehicles will not complete a self-diagnostic test because of emissions-related problem, such as a failed sensor, that must be repaired or replaced. Use BAR’s Auto Shop Locator to find a Smog Check test-and-repair station or repair-only station to diagnose and repair your vehicle.
My vehicle is a specially constructed vehicle (SPCN/kit car), has had an engine change, or has modified emissions parts. Where do I take my vehicle for a Smog Check?
- NOTE: California Vehicle Code section 27156, in part, prohibits modifications to emissions-control equipment or systems without an exemption from the California Air Resources Board (CARB). Modified and add-on parts require an CARB Executive Order (EO). Replacement parts and consolidated parts do not require an exemption.
- For information on engine changes, see our Engine Change Guidelines page.
I received a citation for modified emissions controls or vehicle exhaust noise levels. How do I obtain a certificate of compliance?
If you have been issued a citation for operating a vehicle in violation of Vehicle Code sections 27156 (modified emissions controls) or 27150 or 27151 (modified/loud exhaust), you must take your vehicle to a Smog Check Referee for inspection and complete any necessary repairs. For more information and to schedule an appointment, visit www.asktheref.org.
My vehicle requires a Smog Check, but its catalytic converter was stolen and/or needs to be replaced. What do I do?
A catalytic converter is an essential emissions control part and is a key component inspected during a Smog Check. A licensed Smog Check station will help ensure the correct replacement converter is installed before your vehicle can be inspected. The replacement converter must be from the Original Equipment Manufacturer (OEM) or a California Air Resources Board approved aftermarket converter with an assigned Executive Order (EO) number that meets the exact requirements for your vehicle.
Use BAR’s Auto Shop Locator to find a Smog Check station to complete the installation. For assistance with locating a hard-to-find replacement converter, contact the vehicle manufacturer or Smog Check Referee.
Can the station refuse to inspect my vehicle?
Yes, the station is authorized to refuse a vehicle that is determined to be unsafe to inspect.
DMV Vehicle Registration Renewal Notice
Why does my DMV vehicle registration renewal notice indicate a Smog Check is required at a STAR station?
The STAR Program was created to improve the overall quality of Smog Check inspections and help the state meet required emissions reductions. Accordingly, STAR stations are licensed Smog Check stations that meet higher performance standards set in regulation. Vehicles with a higher likelihood of failure require a Smog Check at a STAR station.
Use BAR’s Auto Shop Locator to find a STAR station near you.
Why does my DMV vehicle registration renewal notice include a smog abatement fee?
California law exempts vehicles eight model years and newer from a biennial Smog Check. In lieu of a Smog Check, owners of these vehicles are required to pay an abatement fee as part of their registration fee to the Department of Motor Vehicles.
What is a Smog Check certification fee?
An $8.25 Smog Check certificate fee is assessed on vehicles once they pass their Smog Check. The certification fee is paid to the station that issues the smog certificate. The fee funds BAR’s administration of the Smog Check Program and consumer protection operations relating to the automotive repair and Smog Check industry.
What is a Smog Check program area?
Air quality varies throughout the state, especially when comparing urban and rural areas. The Smog Check Program establishes three program areas (i.e., enhanced, basic, and change-of-ownership) based on air quality levels and sets requirements for when a Smog Check is required for vehicles registered in each program area. To learn more and to search Smog Check program areas by zip code, visit our Smog Check Program Area Lookup page.
Is the Smog Check Program biased against older vehicles?
No. While California law requires the Smog Check Program to focus on high-polluting vehicles, the Smog Check Program also does not require older vehicles to meet the same emissions standards as newer vehicles. Smog Check emissions standards consider the vehicle type and model year so that a vehicle is never held to a standard that applied when the vehicle was originally manufactured.