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California Emissions Test - 3 Part Inspection Process

First, let's look at the three sections the California Smog Inspection consists of:

2000 Model Year & Newer: 2000 model year and newer vehicles (except vehicles 14,000 GVWR or greater) are exempt from the Emission Inspection portion of the smog check.

These vehicles are administered the new DAD OIS Smog Test which includes a visual smog check inspection and functional inspection for OBD II trouble codes and readiness monitors.

Specific Test Order: The State of California requires smog stations to test vehicles in the specific order listed above. The first inspection (emissions inspection) is performed by the exhaust gas analyzer "smog machine". During this step of the smog check inspection, the smog machine is looking for the presence of Hydrocarbons, Carbon Monoxides and Nitrogen Oxides in your vehicle's exhaust. These are the three (3) undesired chemicals which are responsible for the production of SMOG. The next two inspections, the visual and functional, will be performed both by the smog technician and/or the smog machine.

In order to pass Califoria's emissions test, your vehicle must produce passing results in all three test section.

Enhanced Smog Test - In parts of California where smog pollution is higher, vehicle owners are now required to complete an "Enhanced" version of California's smog test. The "Enhanced" smog test requires your vehicle to be driven on a dynamometer while the smog machine collects emissions samples from the tailpipe. The "Enhanced" smog test has been proven to retrieve a more accurate sample of a vehicle's emissions output, then it's predecessor, the "Basic" smog test. The "Basic" smog test requires vehicles to be tested, only at idle and 2500 rpms. "Basic" smog test vehicles do not need to be driven on a dynomometer.

Basic Smog Test - Counties in California with low smog pollution require the "Basic" smog test. If your county has been added to the "Enhanced" smog test requirement list, the smog stations in your local area will have the neccessary equipment to test your vehicle. No specific action will be required by the vehicle owner.

Change of Ownership - Counties with even less smog pollution are designated as "Change of Ownership" areas. In Change of Ownership parts of the state, smog checks are only required when a vehicle is bought or sold, and when a used vehicle is imported into the state of California.

Which Type Should I Choose?


New vehicles imported into California by the vehicle manufacturer do not need smog checks. These vehicles are California certified during production.

OBDII Smog Machine Link - The State of California now requires all vehicles 1996 and up, to communicate directly with the smog machine during the smog test. This is achieved via your vehicle's OBDII Data Link Connecter. As part of the smog inspection process, the smog technician will connect a Data Cable from the smog machine to your vehicle's OBDII Data Link Plug. This cable will deliver important "Check Engine" codes and "Readiness Flags" from the engine's computer system to the state's smog machine.

Emissions related failure codes will cause your vehicle to fail the smog inspection. The failure codes will be printed on the Vehicle Inspection Report (VIR) which will be given to you by the smog station.

Out-of-State Vehicles - It's true, there is a difference between California and Federal emissions equipped vehicles. And, for the most part California is much stricter when it comes to requiring vehicle manufacturers to equip their vehicles with smog reducing components. However, a used federal vehicle which has all (or only) its federal required emission components, can pass the California smog inspection process and be legally registered in this state. In other words, California will not restrict consumers from purchasing and bringing into the state a used vehicle which is equipped with federal emissions components only, so long as the vehicle was designed that way by the manufacturer. It will however not allow new federal vehicles into the state. New car dealers who wish to sell their products in California must import California emissions equipped vehicles only.