Smog Check Tips for Gasoline-powered and Flex-fuel Passenger Vehicles

Which model-year vehicles require a smog check?

The State of California requires a smog check every other year on any gas-powered, hybrid and flex-fuel vehicle for model year 1976 and newer before the Department of Motor Vehicles (DMV) will issue a registration renewal. The DMV then allows for the following exemptions:

  1. Change of ownership for vehicles four model-years old and newer do not require a smog check.
  2. Registration renewals for vehicles six model-years old and newer do not require a smog check.

Tips for newer model-year vehicles:

Vehicles for model-year 2000 and newer undergo a scan of the On-Board Diagnostic (OBD) system to help determine if the vehicle's emission control systems are operating properly. The State of California's passing criteria combines data from the OBD with a visual inspection.

The following tips will help your car, van, truck, or SUV pass its smog check, and at the same time help the environment!

  • Regular maintenance
    Change your oil and filters as recommended by your vehicle's manufacturer (usually every 3 months or 3,000 miles) to help your vehicle operate efficiently and increase its odds of passing the smog check. It is also important to use the type of oil and fuel recommended by the manufacturer for best performance.
  • Watch for leaks
    Low fluid levels can affect the efficiency and performance of your vehicle, which can cause a test failure.
  • Gas cap required
    State regulations require that your gas cap is in place and is of the correct type for your vehicle to avoid excess evaporative emissions.
  • Watch for warning lights
    The same "On Board Diagnostics" system in your vehicle that triggers the warning light is the same system that reports its information to our inspection station's computer determining if your vehicle meets state requirements, so if your vehicle's computer is triggering a "Check Engine" light, it may not pass the smog check.
  • New or disconnected battery?
    If your battery is disconnected, or if it died and needed a jump start, your vehicle's computer system resets itself and would fail due to a lack of data even if your vehicle is operating properly. Driving between 100 - 150 miles (consult your vehicle's manual for an exact number) before coming in for your smog check will make sure your vehicle has gathered enough information for its test.

Extra tips for older model-year vehicles:

Vehicles for model-year 1999 and older require a tailpipe test to assess the vehicle's smog output.

  • Plan extra time
    Performing a tailpipe test on an older vehicle takes a little more time, usually around 45 minutes from start of the inspection to getting back on the road.
  • Watch for warning signs
    Road-weary vehicles can start to show signs of a faulty emissions system, including difficulty starting or staying running at idle, jumping or shaking at higher speeds, and misfires. Taking your vehicle to a certified repair shop as soon as you notice a worsening trend can catch problems before they escalate into a more major repair or test failure.

Visit a DEKRA smog check station for more expert advice and a fast, professional vehicle inspection. Download a $5 off coupon for your vehicle's next smog check!


State of California Resources

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The State of California answers questions on repair waivers and smog program rules. Visit
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