Underglow is not illegal in Kentucky as long as you follow the state’s color and lighting rules. Any light visible from the front of your vehicle must be white or amber; any light visible from the rear must be white, amber, or red; blue is banned outright on the highway; and no aftermarket light may flash. Stay inside those limits and underglow is legal on Kentucky roads.
Allowed Colors Depend on Where the Light Shows
KRS 189.040(14) is the statute that governs underglow color. It sets two rules for any aftermarket light on the vehicle:
- Lights visible from the front must be white or amber, unless installed as original equipment by the manufacturer.
- Lights visible from the rear must be white, amber, or red, unless installed as original equipment by the manufacturer.
The rule covers any light visible from those angles, not just headlamps and taillights. A green or purple underglow strip whose glow reaches the front of the car violates the statute even though it isn’t a headlight.1Kentucky Legislative Research Commission. Kentucky Revised Statutes 189.040 – Front Lights, Flashing Lights
The statute does not directly address lights visible only from the side. A strip mounted beneath the rocker panels that casts light straight down sits in a gray area, but most kits produce a glow that wraps around the vehicle and becomes visible from the front or rear, which brings 189.040(14) back into play.
The practical takeaway: white or amber underglow running the full length of the car is the safest setup. Amber gives you visible color without any question about compliance. Green, purple, pink, and similar shades are not banned by name, but they fail 189.040(14) the moment they are visible from either end of the vehicle.
Blue Is Off-Limits Entirely
Blue underglow gets its own, stricter prohibition. KRS 189.950(3) makes it illegal to illuminate a solid blue light on any motor vehicle while driving on a highway, and KRS 189.040(15) treats any solid blue light violation as a violation of 189.950(3), which carries heavier consequences than a routine equipment ticket.1Kentucky Legislative Research Commission. Kentucky Revised Statutes 189.040 – Front Lights, Flashing Lights Blue flashing lights are reserved for law enforcement and corrections vehicles under KRS 189.920.2Justia Law. Kentucky Revised Statutes 189.920 – Flashing Lights and Sirens Blue is not a legal underglow color under any circumstances on a public road.
Red Cannot Show on the Front
KRS 189.950(2) prohibits placing a red light on the front of any civilian vehicle and bans red flashing, revolving, or oscillating lights on non-emergency vehicles.3Kentucky Legislative Research Commission. Kentucky Revised Statutes 189.950 – Prohibitions, Exceptions Red underglow at the rear is fine under 189.040(14)(b), but if red light wraps around and becomes visible from the front of the car, you have a violation.
No Flashing, Strobing, or Color-Cycling
KRS 189.040(8) bans flashing lights on all motor vehicles except turn signals and hazard warning lights. This applies to every aftermarket light on the car. An underglow kit set to strobe, pulse, or cycle through colors violates this provision no matter which color it is displaying.1Kentucky Legislative Research Commission. Kentucky Revised Statutes 189.040 – Front Lights, Flashing Lights
KRS 189.920 reserves flashing colors for specific vehicle categories: blue for law enforcement and corrections, red for fire departments, rescue squads, and ambulances, and yellow for public safety, mail, funeral escort, and church bus use.2Justia Law. Kentucky Revised Statutes 189.920 – Flashing Lights and Sirens Flashing underglow in any of those colors invites a stop for mimicking an emergency vehicle on top of the equipment violation.
Glare and Interference With Required Lights
KRS 189.040(5) requires that when you approach an oncoming vehicle within 500 feet, your lights be aimed so glaring rays do not strike the other driver’s eyes.1Kentucky Legislative Research Commission. Kentucky Revised Statutes 189.040 – Front Lights, Flashing Lights For underglow, that means recessing or angling the strips so oncoming drivers see only the glow on the pavement, not the bare LEDs.
KRS 189.020 adds a broader safety standard: every vehicle on a highway must be equipped so it does not create a nuisance and protects other traffic.4FindLaw. Kentucky Revised Statutes 189.020 Underglow bright enough to wash out your brake lights, turn signals, or license plate lamp can draw a citation even when the color itself is compliant. Mounting hardware also cannot block any required lamp or reflector.
What a Ticket Costs
Most underglow violations fall under KRS 189.990, which sets fines of $20 to $100 per offense for violations of KRS 189.020 through 189.040, plus court costs.5Justia Law. Kentucky Revised Statutes 189.990 – Penalties Some officers issue a warning or a fix-it notice on a first offense, but that is discretionary and varies by department.
Blue lights carry a heavier consequence because KRS 189.040(15) routes any solid blue violation through KRS 189.950(3) rather than the standard equipment penalty.1Kentucky Legislative Research Commission. Kentucky Revised Statutes 189.040 – Front Lights, Flashing Lights Flashing red or blue that suggests an emergency vehicle draws a more serious response than a routine equipment stop.
How to Set Up a Compliant Kit
- Stick with white or amber. These are the only colors legal from both ends of the vehicle. Amber is the strongest visible-color option without ambiguity.
- Lock the controller to a single steady color. Disable strobing, pulsing, and color-cycling modes before you leave private property.
- Hide the light source. Mount strips so only reflected light on the ground is visible; exposed LEDs risk a glare citation under KRS 189.040(5).
- Walk around at night and check for light bleed. Underglow that dims your brake lights, turn signals, or plate lamp gives an officer grounds under KRS 189.020.
- Wire a kill switch within reach of the driver’s seat. If you run a non-compliant color at car shows on private property, cut it off before pulling onto a public road.