What’s the California Smog Check?
Cars must go through all sorts of checks and maintenance in order to stay safe and functional. Tires, oil, filters, and breaks are common vehicle components that a mechanic and even the average driver look at regularly.
However, there is one check that is required and specific to certain states. The smog check is a requirement in the state of California as well as several others. It is different from the other kinds of vehicle inspections because this one is meant to keep the environment safe. Read below to learn about the smog check in California and why it is important.
What Does the Smog Check Determine?
In short, a smog check determines if your vehicle produces excess emissions. The inspection measures the number of hydrocarbons, nitrogen oxide, and carbon monoxide in a vehicle’s exhaust.
An inspection involves an exhaust gas analyzer or a “smog machine.” This machine measures the presence of toxic chemicals in the exhaust. Then, a visual and functional inspection is conducted. This part may be performed by either a technician or a smog machine.
Some drivers must complete an “Enhanced” version of the test. This is required in areas of California with higher levels of smog pollution. The “Enhanced” test collects emissions from the tailpipe while the car is being driven.
Afterward, you will be given the results of the inspection. If your car fails the test, you will also be given codes for the repairs that must be made so that your car can pass the test.
Failing a Smog Check
Failing the smog test does not mean that you need a new car. It just means that you will need to make repairs and adjustments to improve your car’s performance and fuel efficiency. Then, you can retest.
However, failing to fix the issues or passing the test will leave you with an unregistered car. This means that legally, you cannot be driving your car. The California Department of Motor Vehicles (DMV) will now allow drivers to renew their car registration without passing the smog check.

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Why California Has This Check
California, especially the highly populated southern part of the state, has long suffered from poor quality air. This is due to both the pollution from humans, specifically the millions of cars and trucks on California roads, as well as the frequent forest fires.
The smog check is one of many of California’s methods for reducing air pollution. This inspection is meant to identify if your car produces too many toxic emissions.
California is the most populated state in the United States with nearly 40 million inhabitants. This amount of people has contributed to intense smog especially within cities. In order to improve the quality of air and prevent it from worsening, the government of California has implemented this strategy to at least reduce human-made pollution.
Who Does This Check Affect?
The California smog check impacts millions of drivers. Basically, vehicles that are 1976 and older are required to undergo a smog check every 2 years. Specifically, cars that are gas-powered, hybrid, or use alternative fuel will need to be checked regularly.
Residents need to get this check every two years after their initial car registration.
Drivers who have purchased a vehicle from another state are also required to get a smog check, even if the car passed a check in another state.
Additionally, this check affects residents selling their vehicles to another California resident. It is the responsibility of the seller to complete a smog test for the car before giving it to a new owner.
Exemptions
Certain types of vehicles are exempt from the smog check. That is because they produce emissions that are below the emissions limits set by the state. These vehicles include:
- Motorcycles.
- Electric-powered cars.
- Those that were made in 1975 or earlier.
- Diesel cars and trucks that are 1997 and older.
- Diesel trucks over 14,500 GVW.
- Those that are 4 years and newer that are being bought or sold.
- Those that are 8 years and newer.
It is important to note that eventually, vehicles that are currently 8 years or newer will eventually need to get a smog check. However, California’s regulations concerning smog check requirements and exemptions may change. So residents must stay informed to make sure that they get their vehicles checked if required.
Author: Katherine Bartlett