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California Law on Car Modifications – Part 4

Light emissions/Neon Underglow Lighting

In California, neon underglow lights are quite slightly, becoming a rage and are legal to use, but , of course, there are some restrictions. Before installing and using such neon underglow lighting, be sure to check to confirm what is permitted.  The following will set forth some of the basic guidelines in California relating to neon car and vehicle lights.

California’s Department of Motor Vehicles (DMV) regulates neon underglow lighting.  The DMV permits LED lights which emit a diffused non-glaring light which is less than 0.05 candela per square inch (1 candela is essentially equal to the light emitted from one candle).   You are advised to check your neon lights’ luminosity when buying them to be certain they are within the standards set and required by the California DMV.

Size and position of Neon Underglow Lighting

There are other rules and restriction on size and position of neon underglow lights attached to a car or other motor vehicle:

  • It must not alter other required safety lighting. Lights must not replace or disrupt any of your vehicle’s required existing lights (such as tail lights, break lights, turn signals, or headlights)
  • It must not be too close to other safety lighting. Neon lights also must not be installed within 12 inches of any required light, lamp, reflector or other required device on your vehicle
  • The size of the neon underglow is limited, The size of the underglow must not be larger than 720 square inches, unless your vehicle is authorized to display signs.
  • The positioning of lighting is also limited Internally illuminated sign in a car or other motor vehicle is permitted if it is less than 0.25 candela per square inch, it must not contain a white background, and it may only be displayed on each side of the car or other vehicle and not on front or rear of the car or other vehicle.

Restricted colors

There are restrictions in California on color and placement of such lighting.  According to California law a car or other vehicle may not display the color red at the front.   The apparent reason is red is used as a warning in the rear of cars and other vehicles, including becoming brighter when brakes are applied.  Further, in California one may use any colors for the underglow lighting, except for the above-mentioned restriction on the color of red at the front of a car or other motor vehicle.

Although we did not see any restriction on flashing lights (which restriction might be expected), it’s advised NOT to use any kind of flashing lights.  Such flashing lights might be mistaken as a police vehicle or distract another driver, causing a collision, possibly resulting in property damage and/or injuries, civil liability and substantial monetary damages against the offender!


Underglow neon lighting systems and other lighting which is outside the law may result in receiving a non-moving traffic violation, in which case the offender will be required to modify his or her car or other motor vehicle to conform to California codes and regulations, as well as pay a fine, and possibly civil liability for any damages caused to others.


We trust you found this article both useful and interesting.  One purpose is to prevent our readers from incurring costs for unlawful car and vehicle modifications that may be required not only to be removed but also may subject our readers to fines and other penalties.  If you are aware of any other interesting or noteworthy laws and rules concerning car and other motor vehicle modifications, please send them to us.

Thanks for your interest and drive safely!

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