Clean Air Blog

California Smog Inspection FAQ

Here are the most frequently asked questions about California's emissions inspections, answered by our STAR Certified technicians at Lake Smog Test Only in Pasadena.

What is a smog check?

A smog check is a state-mandated inspection of your vehicle's emission control systems to ensure they meet California's air quality standards. A certified technician connects diagnostic equipment to your vehicle—typically through the OBD-II (On-Board Diagnostics) port under your dashboard—to check for emissions-related faults, read diagnostic trouble codes, and verify that your vehicle's internal self-tests have completed successfully.

How often do I need a smog check?

Most vehicles in California need a smog check every two years when renewing their registration. Your DMV registration renewal notice will indicate if a smog check is required. New vehicles are generally exempt for the first eight model years. During this exempt period, owners pay an annual "smog abatement fee" instead. Learn more about how often you need a smog check in California.

How much does a smog check cost?

Inspection fees are not regulated by the state and vary by station, region, and vehicle type — our smog check cost guide breaks down exactly how the pricing works. In addition, there is a state-mandated $8.25 smog certificate fee if your vehicle passes. This fee is fixed and cannot be marked up by any station. At Lake Smog Test Only, we offer competitive pricing and periodic smog test coupons to help you save.

How long does a smog check take?

A standard smog inspection typically takes 15 to 30 minutes from the time the technician begins testing. Wait times can vary depending on how busy the station is. At Lake Smog Test Only, walk-ins are always welcome and we work to get you in and out as quickly as possible. Learn more about the full testing process.

What happens if my car fails a smog check?

If your vehicle fails, you will receive a Vehicle Inspection Report (VIR) detailing the specific reasons for the failure. You'll need to take the VIR to a licensed smog repair station for diagnosis and repairs, then return for a retest. California offers financial assistance through the Consumer Assistance Program (CAP) for qualifying vehicle owners who need help paying for emissions-related repairs. Read our detailed guide on what happens when your car fails a smog test.

Do I need a smog check when buying or selling a car?

Yes. A smog certification is generally required for change of ownership if the vehicle is more than four model years old. The seller is typically responsible for providing a valid smog certificate. Vehicles that are four model years old or newer, or those manufactured before 1976, are generally exempt from this requirement.

Which vehicles are exempt from smog checks?

Several categories of vehicles are exempt from California's biennial smog check:

• Older vehicles: Gasoline-powered vehicles model year 1975 or older
• Newer vehicles: Vehicles less than eight model years old
• Electric vehicles: Fully electric vehicles, including battery EVs
• Motorcycles and trailers
• Older diesel vehicles: Diesel-powered vehicles model year 1997 or older

For a comprehensive list, see our article on which cars are exempt from smog checks in California.

What is a STAR Certified station?

STAR stations are authorized by the Bureau of Automotive Repair (BAR) to perform smog checks on all vehicles, including those specifically directed by the DMV. These stations must meet higher performance and accuracy standards and are subject to more frequent monitoring. If your DMV registration renewal notice says "Smog Certification Required at a STAR Station," you must take your vehicle to a STAR-certified facility like Lake Smog Test Only. Learn more about the different types of smog test stations in California.

What is the difference between a "Test Only" and a "Test and Repair" station?

A Test Only station like Lake Smog Test Only is authorized exclusively to perform smog inspections. We do not perform repairs, which means there is no financial incentive to find problems that do not exist. A Test and Repair station can both inspect and repair vehicles. The DMV may direct certain vehicles to Test Only or STAR stations for enhanced oversight.

What should I bring to my smog check?

While we can look up your vehicle electronically, bringing your DMV registration renewal notice speeds up the process. You should also bring your vehicle registration card and a valid form of payment. Read our full guide on what to bring to a smog check in California.

How should I prepare my vehicle for a smog check?

• Drive for 20 minutes: Warm up the engine and catalytic converter before arriving.
• Check your engine light: If the MIL (Check Engine Light) is on, your vehicle will automatically fail. Have it diagnosed before your appointment.
• Verify your gas cap: Make sure it seals properly and clicks when tightened.
• Allow readiness monitors to complete: If your battery was recently disconnected or replaced, drive the vehicle for at least a week. As of 2025, all OBD-II readiness monitors must show "Ready" status to pass.
• Check for leaks: Visible oil or coolant leaks in the engine bay can cause a visual inspection failure.

Do I need a smog check for an out-of-state vehicle?

Yes. If you are registering a vehicle in California for the first time that was previously registered in another state, it must pass a California smog check. This applies regardless of the vehicle's age (with standard exemptions for pre-1976 gasoline vehicles and pre-1998 diesel vehicles).

Have more questions? Call Lake Smog Test Only at (626) 798-0049 or stop by our location at 765 E. Washington Blvd. in Pasadena. Walk-ins are always welcome.