Smog Test

SAFETY - Make sure your tires are in good condition and properly inflated. Make sure the "check engine" light or any other dashboard warning lights are NOT on. Make sure that your vehicle has no fluid leaks and no safety issues. Remember, your vehicle will be strapped down on a dynamometer and required to perform flawlessly under stressful conditions.

VEHICLE MAINTENANCE AND PREPARATION - Don't change the size of the tires from the original specifications. The dynamometer test equipment is calibrated to the "stock" tire size. Over- or under-sized tires will alter the speed calculations performed by the test equipment and may prevent your vehicle from going through the test since the machine won't sense the correct speed for your vehicle's tire size. Make sure your vehicle has a clean air filter and fresh engine oil.

Make sure your vehicle's gasoline cap fits your vehicle, isn't damaged and is turned tightly in place. A vehicle without a gas cap is an automatic Smog Check test failure. The week of the Smog Check test, take the vehicle out for an extended drive, preferably on the freeway and especially if you're regularly a "short trip" driver. Drive approximately 30 minutes or longer at varying speeds on freeways, surface streets and up hills.

THE DAY OF THE SMOG CHECK TEST - Fill the gas tank of your vehicle with the grade of fuel stated in the owner's manual. Make sure all fluids are topped off and that all non-essential items are removed from the trunk or the rear of the vehicle. The dynamometer weighs your vehicle before the test, and if the vehicle is heavier than it should be, the weight will make it harder to pass. Drive at least 30 minutes before arriving at the Smog Check test facility to ensure the car or truck has reached full operating temperature.

Ask the repair facility if they can perform the test within 15 minutes of your arrival. This will let the vehicle return to normal operating temperature quickly. Remember to bring the DMV renewal notice with you to the repair facility. The paperwork has a bar code on it that needs to be scanned for the Smog Check test. If you don't have the paperwork, the repair facility may charge you for the extra time it takes to input the vehicle identification number that they could pick up from the bar code.

Active Stations:

Stations with inspection activities during the time period. This count differs from the number of stations licensed because a station that is licensed to do smog inspections may not have any activity during a particular time period.

Licensed Technicians:

A count of licensed technicians. Some licensed technicians may not be assigned to stations. Counts are broken down by license classification:

  • EA - licensed to conduct BAR-97 loaded-mode tests (ASM) in Enhanced areas as well as BAR-90 (TSI) tests,

  • EB - licensed to conduct BAR-90 (TSI) tests in basic and change-of-ownership areas,

  • EU - formerly an advanced license, this classification is being phased out.

Basic: Refers to those portions of the state with moderate air pollution. Biennial testing (every two years) is required in Basic areas. The two-speed idle test is used in Basic Areas; dynamometer testing is not required.

Certificates Issued - Counts all Smog Check inspections resulting in the issue of a certificate, or waivers resulting in the issue of a certificate.

Change of Ownership - These are predominantly rural areas of the state with the cleanest air. Vehicles registered in Change-of-Ownership areas require testing only during a sale or prior to initial California registration. The two-speed idle test is used in Basic Areas; dynamometer testing is not required.

Cost Waiver - The Repair Cost Waiver allows a vehicle to be registered without passing its Smog Check inspection. A motorist must spend $450 on emissions-related repairs by a licensed Smog Check technician at a licensed Smog Check station in order to qualify for a Repair Cost Waiver.

Station Types:

  • REG - Regular - Licensed to perform official smog inspections and repairs. Prohibited from issuing certificates to Gross Polluters.

  • GS - Gold Shield - Licensed to perform official smog inspections and repairs. Issue certificates to Gross Polluters; perform state-subsidized repairs; perform the "after repairs" certification test on vehicles that were directed to, and failed their Smog Check at a Test-Only station, provided that the vehicles were repaired at the Gold Shield station.

  • TST - Test Only - Licensed to perform official smog inspections and issue certificates to all vehicles. Prohibited from performing all diagnostics and repairs.

  • REF - Referee - Issues repair cost waivers and economic hardship exemptions, inspects vehicles granted limited parts exemptions, inspects vehicles with engine changes, inspects gray-market and special construction vehicles, and resolves disputes between customers and Smog Check stations.

  • Gov. Fl. - Government Fleets - sites established by government agencies to test their vehicles.

  • Bus. Fl. - Business Fleets - sites established by businesses and corporations to test fleets which they manage.

Enhanced - These are the areas of the state with the most severe air pollution, as determined by the United States Environmental Protection Agency. Biennial inspection (every two years) using the BAR-97 loaded-mode (dynamometer) test is required for vehicles registered in Enhanced areas. Vehicles must also be inspected when sold, or upon initial California registration.

Failure Types

  • Gross Polluter: A subset of tailpipe failures, gross polluters emit the most pollution of all failures, usually double the allowable limit or more.

  • Tailpipe: Any vehicle which fails because of excessive concentration of pollutants as measured at the tailpipe.

  • Functional: The gas cap test, ignition timing and exhaust gas recalculation (EGR) check are part of the functional test.

  • Visual: Missing, modified or disconnected emissions parts as noted by the technician during their visual inspection of the vehicle.
Note: the above categories are not mutually exclusive -- a vehicle may be counted in any combination of them.

Hardship - The Economic Hardship Extension allows a vehicle to be registered immediately without passing its Smog Check inspection and gives a vehicle owner up to two years to complete the repairs needed to bring the vehicle into compliance with emissions standards. To obtain an extension, a vehicle must be brought to a Referee Center, where tests may be performed.

First Test - This is the first test on any vehicle for an inspection cycle. If a vehicle has not been tested for 180 days prior to a test, then that test is considered an initial episode test regardless of the outcome of any prior test. No tests in the 180 days following an initial episode test are considered as an initial episode tests regardless of the outcome of any intervening tests.

Referee Activity - Tests performed and waivers or extensions issued at "Referee" sites.

Unique Vehicles - Includes all unique vehicle identification (VIN) or license plate numbers. If a vehicle failed during the previous time period and passed an after-repairs test during the current one, it will be included. If it fails during the current period and gets a certificate or other tests later, it is included in the report.

Vehicle Information Database - The Bureau of Automotive Repair's central Smog Check computer, which transmits vehicle information to, and collects test result information from, Smog Check station test equipment.

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Written by
Co-Founder and CEO of
35 years in the automotive repair field, ASE Master Technician, Advanced Electrical and Mechanical Theory.


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Article first published (Updated 2013-08-16)