What is a STAR smog test? A guide to California’s requirements

Most California vehicles subject to the state's Smog Check Program periodically need an emissions inspection. But some vehicle owners, including fleet managers of commercial vehicles, receive a registration renewal notice that specifically requires a STAR smog check.

A STAR smog test is nearly identical to a standard California smog check, but it’s performed at a station that meets additional performance standards established by the California Bureau of Automotive Repair (BAR). Vehicles may be directed to a STAR smog check station based on their emissions profile, past smog check failures or selected as part of a random state sample.

For fleets, knowing which vehicles require a STAR smog check and preparing them for inspection can help reduce failed tests, repeat trips and unnecessary vehicle downtime.

What is a STAR smog station and why was my vehicle flagged?

A STAR smog check station is a California-licensed smog check station that has earned additional certification from BAR. STAR stations must meet and maintain higher inspection-based performance standards and have the equipment needed to inspect vehicles directed to the STAR program.

Why do I need a STAR smog check for my California registration renewal?

If your California DMV registration renewal notice says "Smog Certification Required at a STAR station," your vehicle must be inspected and certified at a STAR smog check station.

BAR currently directs vehicles to STAR stations for three primary reasons:

• High Emitter Profile (HEP): BAR uses smog check inspection data to identify vehicles with a greater likelihood of failing an inspection. The High Emitter Profile considers factors such as model year, make and model, engine displacement, transmission type, odometer reading and previous inspection results.
• Random sampling: For program evaluation, 2% of vehicles in certain, more highly polluted areas subject to California's Enhanced Smog Check Program are randomly selected for certification at a STAR station.
• Gross Polluter: A vehicle that fails a smog check with emissions exceeding BAR's established gross polluter limits must be certified at a STAR station or, when applicable, a Referee facility.

Being selected for a STAR smog test therefore does not necessarily mean BAR knows there is something wrong with your vehicle. Your registration renewal notice will tell you whether STAR certification is required.

What does STAR certified smog mean?

STAR certification applies to the smog check STAR station, not to a different type of emissions test.

STAR-certified test-only and test-and-repair stations can inspect vehicles specifically directed to the STAR Program. In practical terms, if your DMV notice requires a STAR smog check, a standard non-STAR smog check station cannot provide the certification you need.

Does California require STAR smog checks for all vehicles?

No. STAR inspections apply only to certain vehicles that are already subject to California's Smog Check Program and are specifically directed to a STAR station. Your DMV registration renewal notice will state "Smog Certification Required at a STAR station" if your vehicle needs one.

California's broader smog check requirements depend on the vehicle's model year, fuel type, weight and reason for inspection. For example:

• Gasoline, hybrid and alternative-fuel vehicles: Model year 1976 and newer generally require smog check inspections. However, vehicles eight model years and newer are exempt for registration renewal and instead pay a smog abatement fee.
• Diesel vehicles: Model year 1998 and newer are subject to smog check unless the vehicle has a GVWR greater than 14,000 pounds.
• Heavy-duty diesel and alternative-fuel vehicles: Nearly all vehicles over 14,000 pounds GVWR that operate on California public roads are instead generally subject to the California Air Resources Board's Clean Truck Check emissions program.
• Electric vehicles: EVs are exempt from the Smog Check Program.
• Older vehicles: Gasoline, hybrid and alternative-fuel vehicles from model year 1975 and earlier and diesel vehicles from model year 1997 and earlier are exempt.

The rules also differ for a change of ownership. Gasoline, hybrid and alternative-fuel vehicles four model years and newer are generally exempt from smog check when ownership changes and instead require a smog transfer fee.

Test-only vs. test-and-repair: How do smog check STAR stations work?

The main difference between STAR test-only and STAR test-and-repair stations is what happens if the vehicle has an emissions problem.

• A STAR test-only station can inspect and certify the vehicle, but it cannot diagnose or repair emissions problems. If the vehicle fails, you will need to take it elsewhere for repairs before having it retested.
• A STAR test-and-repair station can perform both the inspection and emissions-related repairs. That may reduce the number of locations a fleet needs to coordinate if a vehicle fails its inspection.

What is a STAR station smog check process during inspection?

A STAR smog check follows California smog check inspection requirements. The exact procedures depend on the vehicle's model year, fuel type, GVWR and where it is registered.

When you arrive at a STAR smog check station, bring your DMV registration renewal notice if you have it. The station will verify your vehicle information and perform the smog check procedures required for your vehicle.

For most model year 2000 and newer vehicles, the inspector connects to the vehicle's on-board diagnostic (OBD) system to check emissions-related information. The inspection may also include visual and functional checks of emissions-control equipment. Pre-2000 vehicles generally undergo a tailpipe emissions test instead.

The inspection usually takes about 30 minutes. Once it's complete, the station will give you a vehicle inspection report showing whether the vehicle passed or failed. If it passes, the station issues a smog certificate and electronically sends it to the DMV, so you don't have to submit the certificate yourself. You can then complete your vehicle registration renewal.

How to pass a STAR smog test on your first try

There's no way to guarantee a passing result, but you can take a few steps to help avoid common reasons for a failed or incomplete inspection.

Before sending a vehicle to a STAR smog check station:

• Check for an illuminated check engine or malfunction indicator light.
• Address known emissions-related diagnostic trouble codes (DTCs).
• Keep up with scheduled vehicle maintenance and needed repairs.
• Make sure OBD readiness monitors have had an opportunity to complete, particularly after repairs, battery disconnection or clearing diagnostic codes.
• Bring the DMV registration renewal notice, if available.

OBD readiness is particularly important because the vehicle's diagnostic system needs time to complete emissions-related self-tests. Clearing a code immediately before an inspection does not necessarily solve the underlying problem and can reset readiness monitors.

For fleets managing multiple vehicles, telematics can help identify DTCs and other vehicle health information before a scheduled inspection. Verizon Connect's Emission System Report provides information about emissions-related systems, including fault and diagnostic trouble codes, check engine light status and how long or how far a vehicle has traveled with the light illuminated. It can also help manage fleet maintenance documentation for a fuller view of vehicle health at the ready.

That additional visibility from cloud-based fleet management software can help fleet managers identify vehicles that may need attention before sending them for an emissions inspection.

How much time is your fleet losing to inspections and compliance tasks? See where technology can help in A Guide to Compliance Management for Fleet Vehicles.

How much does a STAR smog check cost?

There is no single statewide price for a STAR smog check. BAR does not regulate Smog check inspection prices, so the cost varies by station and vehicle.

Stations are required to post their inspection prices and provide an estimate before beginning the inspection. California also requires an $8.25 smog check certificate fee.

BAR's 2025 smog check data reported average inspection costs of about $61 at STAR test-only stations and $69 at STAR test-and-repair stations.1 However, BAR notes that reported costs may include discounts and may not represent the actual amount an individual customer pays.

For fleet operators, the direct inspection price is only part of the potential cost. Travel to and from the STAR smog check station, employee time and taking a vehicle out of service can add to the operational impact of required emissions testing.

What if fewer fleet inspections meant less downtime? See how connected vehicle technology is changing compliance for public fleets in Connected Vehicle Technology for State and Municipal Operations.

Is STAR smog more expensive than a standard inspection?

Not necessarily.

Because California does not set smog check inspection prices, individual STAR and non-STAR stations establish their own rates. BAR's statewide inspection data does not show that STAR inspections are consistently more expensive than comparable inspections at non-STAR stations.

If your vehicle is directed to do a STAR smog check, make sure you compare prices only among STAR-certified smog check stations. This way you can find the best price for the type of inspection that fulfills your legal requirement.

How do you find a STAR smog check station in California?

If your DMV renewal notice requires a STAR smog check, use the California Bureau of Automotive Repair's Auto Shop Locator to find an appropriately certified station.

The locator can help drivers and fleet managers find STAR smog check stations in San Diego, Fresno, Los Angeles, Sacramento and communities throughout California. Before scheduling an inspection, confirm that the location is STAR certified and can inspect your particular type of vehicle.

For fleets, it can also be useful to decide whether a STAR test-only or test-and-repair station better fits your needs. A test-only station may be sufficient for a well-maintained vehicle with no known emissions issues, while a test-and-repair station can diagnose and address emissions problems if repairs are needed.

Did you know? California government fleets may have another option for managing Smog Check Program requirements. Eligible government vehicles can participate in BAR's Continuous Testing Program (CTP), which uses approved telematics platforms, including Verizon Connect Reveal, to continuously submit emissions-related OBD data to BAR as an alternative to standard biennial smog check inspections.

Smog checks and STAR smog checks are only one part of managing vehicle health and regulatory requirements across a fleet. Understanding which vehicles need testing, identifying emissions issues early and keeping accurate maintenance information can make compliance easier to manage.

Smog checks are just one part of a healthy fleet. Download our Fleet Management Software Buyer's Guide to find a platform that provides the diagnostics and emissions reporting your business needs.

Sources

¹ "Smog Check Executive Summary Report 2025," California Bureau of Automotive Repair (BAR)