In order to legally drive in California, you need to have a smoke check on all your vehicles that are older than 6 years once every two years, or every year if you own a high-polluting vehicle. But how do smoke tests work? How is the vehicle inspection actually done?
Only licensed technicians are able to perform a vehicle inspection. They will need to attach some equipment to your vehicle to measure pollutants.
The smog test consists of three different testings – functional inspection, visual inspection, and emissions inspection. Functional and visual inspections will allow the technicians to measure pollutants that your car is releasing. These include oxygen (O2), hydrocarbons (HC), carbon dioxide (CO2), and carbon monoxide (CO). These are usually the most common pollutants measured. However, in some of the US most polluted urban areas, you may also have your vehicle checked for oxides of nitrogen (NOx).
All the measurements that are taken from your vehicle during the smog test will be immediately sent to your state’s agency that is responsible for monitoring vehicle emissions and smog. If you live in California, the measurements will be sent to the Bureau of Automotive Repair (BAR), while if you live in Georgia, for example, the measurements are sent to the Georgia Clean Air Force (GCAF).
Depending on the county, state, or city where your vehicle is registered with DMV, the smog tests may be different. Here are the most commonly used testings that are used:
#1: Acceleration Simulation Mode (ASM):
By using a dynamometer, this test simulates different driving conditions. This is one test that is usually performed in older vehicles.
#2: Two-Speed Idle (TSI):
This is also known as the tailpipe emissions inspection. This test allows the technician to analyze the exhaustion emissions with the engine idling high first, and then low. This test is usually only performed in cars that were registered before 1995.
#3: On-Board Diagnostics (OBDI):
This test only consists about downloading the information provided in the vehicle’s on-board diagnostics computer.
As soon as the smog test is completed, and no matter if your vehicle passed or failed the test, the technician will provide you a copy of the test results – the Vehicle Inspection Report (VIR), as well as a receipt for the smog check payment.
Please note that if your vehicle didn’t pass the smog check, you won’t be able to drive it on public roads. In case you opt to do so and you are caught, you will get a ticket.
The best thing you can and should do in the case your vehicle didn’t pass the smog check is to go to a licensed test and repair station to have it repaired. After that, and in order to be able to drive your vehicle on public roads again, you’ll need to do the smog check once again.