California Smog Check 101

What is a smog check?

A smog check is an inspection that examines the vehicle’s exhaust and checks to make sure that your vehicle isn’t pushing harmful pollutants and chemicals into the environment. Smog checks are often grouped with or referred to as a vehicle’s emissions test.

Through the Reagan Administration, the Clean Air Act of 1966, was put into place to combat pollutants that had plagued Los Angeles as far back as 1943. Initially, the smog pollution was pinpointed to the power plants that surrounded the area, causingresidents to experience nausea, burning eyes and lungs. After the power plants were regulated, they noticed the smog continued. It was from this, officials narrowed it down to vehicles.

To further minimize exposure to pollutants, smog checks were put in place to identify vehicles that release tailpipe emissions.

How to prepare for a smog check inspection?

Here is a list of items to explore prior to inspection:

  • Clearing the check engine light – if your check engine light is on, do not ignore this. This light will automatically result in a failed smog test. Be sure to get the Diagnostic Trouble Code read to identify the issue and get it fixed.
  • Get an oil change – having fresh oil eliminates the traces of harmful chemicals and pollutants that may have formed in older oil
  • Schedule a vehicle checkup or pre-inspection – it’s always a good practice to keep up with your vehicle’s regular maintenance schedule. This allows for you to get an idea of any underlying issues prior to your smog test. Also, you will want to complete this in advance of the smog check in case your battery was replaced or disconnected – the vehicle’s internal systems can be altered, resulting in a possible failure
  • Drive vehicle on the highway – driving at higher speeds can help release any traces of pollutants such as oil or gas out of the system

Common Ways to Fail Smog Checks

While this isn’t an exhaustive list, here are some common reasons why your vehicle wouldn’t pass a smog check inspection:

  • A high volume of pollutants found in tailpipe
  • Emissions system fault codes are present
  • Battery replaced or disconnected – this alters the vehicle’s internal systems
  • Readiness monitors (OBD-II) aren’t complete – readiness monitors self-test the vehicle’s emission control system

Identifying Readiness Monitors Completion & Fault Codes

Your vehicle’s check engine light is an indicator if the readiness monitor is finished or not. To test, turn the key in the ignition without starting the car. The check engine light should remain on – if it flashes after 15 seconds, then the readiness monitors aren’t complete.

Also, it is important to note that fault codes can’t be hidden by erasing or if the battery is disconnected – the readiness monitors must be completed.

Smog Check Inspection FAQs

How much does a smog check inspection cost?

The cost can range between $30-$60 – this depends on the type of vehicle being tested.

How often is the smog check inspection required?

It is required biannually or every two years.

What does the smog check inspection consist of?

The inspection consists of four main tests:

  • Visual inspection of the emissions equipment and systems
  • Functional inspection of the vehicle’s check engine light, ignition timing, exhaust gas recirculation system, fuel evaporative system, and gas cap
  • Functional inspection of the vehicle’s onboard diagnostic (OBD-II) system
  • Tailpipe emissions inspection

Who can administer the smog check inspection in California?

The smog check inspection in administered by the California Department of Consumer Affairs’ Bureau of Automotive Repair and has over 7,000 independent-owned Smog Check stations.

Are there vehicles where the smog check is not a requirement?

Yes, any vehicles that were manufactured in or before 1976.

What vehicles have smog check exemptions?

  • Gas-powered vehicles, motorcycles and trailers that are a 1975-year model or older
  • A diesel-powered vehicle, 1997-year or older model OR has a Gross Vehicle Weight Rating (GVWR) of over 14,000 lbs.
  • A natural gas-powered vehicle thatweighs more than 14,000 lbs.
  • An electric vehicle

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