What happens during a smog check


One of the important part of state’s efforts in order to improve the air one breathe is Smog check program. This inspection of smog check is designed to identify the excess emissions of the vehicles, and to be properly repaired accordingly. The main aim of the program is to reduce the air pollution created by the cars, which are in millions in California. El Cajon is a city surrounded by mountains in San Diego county (California, united states). Smog check in el Cajon is mandatory to renew the registration of the vehicles.

Even the new residents to California state are required to undergo an initial inspection to register(vehicles). For most of the vehicles, the smog check is required for every two years. A smog inspection is needed on the vehicles that are older than six model years for every 2 years, and once if a vehicle is tagged as the most polluting. There exist some exemptions for smog inspection, even California require every vehicle to undergo smog check:

Natural gas-powered vehicles

Electric vehicles

Gasoline powered vehicles model year 1975 and older

Motor vehicles

Diesel powered vehicles which:

Are 1997 model year and older (or)

Gross weight rating of over 14,000 lbs

Testing methods:

Technician(licensed) will attach a measuring equipment to the vehicle in order to perform the inspection

Functional and visual inspection:

Ensure the functioning, to check emissions equipment is in place and also to reduce the air pollution from car’s exhaust.

Emissions inspection:

Emissions measured include carbon dioxide (CO2), oxygen(O2), oxides of nitrogen(NOx) and carbon monoxide(CO).

Current testing methods:

Following are the current testing methods:

On board diagnostics:

While performing this test, with the help of vehicles on-board diagnostics computer, information is downloaded.

Two-speed idle:

It is usually performed for the older cars that are registered before 1995, and this test helps us to analyze the exhaust emissions from the tail pipe as the engine idles, generally first at high and later at low speed.

Acceleration simulation mode:

With the help of drive-on dynamometer (kind of treadmill for the car), acceleration simulation mode test emissions under simulated driving conditions and is most often reserved for older vehicles.

Hybrid vehicles, gasoline powered vehicles, alternative -fuel vehicles (model year 1976) and newer require a smog check. Generally, smog check in el Cajon is administered by California Department of Consumer Affairs’ Bureau of Automotive Repair (BAR). More than 7000 vehicles are inspected every year throughout the state which are state licensed and independently owned stations. Measurements are recorded immediately and become available to state’s agency responsible for vehicle emissions and monitoring smog.


After the completion of smog check, technician will hand over you the copy of the test results (pass or fail), called the vehicle inspection report, along with the payment receipt.

One can legally drive in California if the vehicle passes the inspection.

If the vehicle fails in the inspection (smog test), one will receive instructions on what needs to get repaired. Hence, checking the vehicle on time and driving safe is recommended.