Smog Check Tips for Diesel Vehicles

The State of California now requires all diesel vehicles 1998 and newer with a gross vehicle weight rating of up to 14,000 pounds to pass an inspection prior to vehicle registration renewal or at change of ownership (buying or selling).

The diesel vehicle inspection is similar to a gasoline-powered vehicle and includes a scan of the diesel vehicle's On-Board Diagnostic system, a visual inspection of emissions components and a visible smoke test.

The following tips will help your diesel vehicle 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.

Visit a DEKRA smog check station for more expert advice and a fast, professional vehicle inspection on your diesel, gasoline-powered or hybrid vehicle. Download a $5 off coupon for your vehicle's next smog check!

State of California Resources

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Learn more about special requirements for diesel vehicles including approved aftermarket parts.

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