Colorado’s vehicle light laws require every car and truck on public roads to have working headlights, taillights, turn signals, brake lights, and a lit rear license plate, with specific rules on when the lights must be on, how far they must be visible, and what colors are allowed. Most of the requirements sit in Title 42, Article 4, Part 2 of the Colorado Revised Statutes. Federal manufacturing standards under FMVSS No. 108 apply on top of those. Drivers who miss even basic requirements risk citations, and aftermarket changes like LED bulb swaps or light bars carry restrictions that catch a lot of owners off guard.
When Headlights and Taillights Are Required
Headlights must be on between sunset and sunrise, and during any condition that limits visibility, including fog, snow, and heavy rain.1Justia. Colorado Code 42-4-204 – When Lighted Lamps Are Required High beams must illuminate objects at least 350 feet ahead, and low beams at least 100 feet. Switch to low beams when you’re following another vehicle closely or approaching oncoming traffic.
Taillights must be red and visible from at least 500 feet to the rear.1Justia. Colorado Code 42-4-204 – When Lighted Lamps Are Required Your rear license plate must be illuminated by a white light so it’s legible from behind. People forget the plate light when replacing tail assemblies or installing aftermarket housings, and it’s an easy ticket at a traffic stop.
A modern trap: daytime running lights often activate the front lamps only. Driving at dusk or in rain with just DRLs on leaves your rear end effectively invisible from behind. If your vehicle has an “AUTO” headlight setting, use it, but don’t assume the sensor always catches fog or intermittent rain in time.
Turn Signals and Brake Lights
Turn signals must be activated continuously for at least the last 100 feet before turning in urban areas. On roads where the speed limit exceeds 40 mph, that distance doubles to 200 feet.2Justia. Colorado Code 42-4-903 – Turning Movements and Required Signals You also have to signal before suddenly slowing or stopping when there’s a vehicle immediately behind you and you have an opportunity to do so.
Brake lights must emit red light visible from behind during daylight. A burned-out brake bulb is one of the most common reasons for a traffic stop in Colorado, and it’s worth checking every few months since you can’t see it yourself from the driver’s seat.
Fog Lights and Auxiliary Lamps
Fog lights are permitted in poor-visibility conditions but cannot replace your standard headlights.3Justia. Colorado Code 42-4-212 – Special Restrictions on Lamps Running fog lamps alone on a clear night is a violation, even if the road looks well lit to you. Fog lights sit low and cast a short, wide beam that doesn’t meet the distance requirements for headlamps.
Side cowl and fender lamps are allowed, limited to two per vehicle, and must emit amber or white light without producing glare.4Justia. Colorado Code 42-4-215 – Additional Lighting Equipment Decorative underbody or accent lighting is generally allowed as long as it doesn’t flash, strobe, or display colors reserved for emergency vehicles.
Aftermarket Modifications
Aftermarket lighting is where Colorado drivers get in trouble most often. Two layers apply: federal manufacturing standards from NHTSA, and Colorado’s installation and use rules.
LED and HID Conversion Kits
Swapping factory halogen bulbs for LED or HID replacements in an existing halogen housing is more complicated than online product listings suggest. Under FMVSS No. 108, every replaceable headlight bulb must conform to dimensions and electrical specifications formally accepted by NHTSA. As of early 2024, no LED light source has been listed in NHTSA’s docket for use as a replaceable bulb in a halogen headlamp housing.5National Highway Traffic Safety Administration. 571.108 NCC-230201-001 LED Headlights M. Baker Manufacturers can’t legally sell LED drop-in replacements for halogen headlamps as compliant equipment.
NHTSA regulates the manufacture and sale of the equipment but generally leaves enforcement of individual modifications to state law.5National Highway Traffic Safety Administration. 571.108 NCC-230201-001 LED Headlights M. Baker A Colorado officer won’t check an NHTSA docket at the roadside, but will notice excessive glare, improper beam patterns, or a non-white color. LED bulbs installed in halogen reflector housings frequently fail on all three because the light source sits in the wrong position relative to the reflector’s focal point.
Complete factory-designed LED headlamp assemblies are a different matter. If the whole unit is engineered with LEDs and meets FMVSS No. 108 photometry and color requirements, it’s federally compliant.5National Highway Traffic Safety Administration. 571.108 NCC-230201-001 LED Headlights M. Baker Replacing the entire headlight assembly with a DOT-compliant LED unit is the legally safe path to brighter lighting.
LED Light Bars
Light bars are popular on Colorado trucks and SUVs but are restricted on public roads. Colorado’s auxiliary lighting rules require driving lamps to comply with brightness and glare limits, and high-powered off-road bars far exceed what’s allowed on-road.4Justia. Colorado Code 42-4-215 – Additional Lighting Equipment Colorado’s statute doesn’t spell out a cover requirement in so many words, but running an uncovered, activated light bar on a public road will draw a citation for excessive glare or non-compliant auxiliary lighting. The safest approach is to keep the bar off and covered on public roads.
Tinted or Smoked Taillight Covers
Tint film and smoked covers on taillights and brake lights lean heavily toward illegal in Colorado. The 500-foot rear visibility standard doesn’t change because you added a film. Any tint that dims the light enough to compromise visibility puts you out of compliance. The darker the tint, the more obvious the violation, and an officer doesn’t need a light meter to write the ticket.
Prohibited Colors and Flashing Lights
Red or blue lights visible from the front of a non-emergency vehicle are specifically prohibited.3Justia. Colorado Code 42-4-212 – Special Restrictions on Lamps Flashing or strobing lights on non-emergency vehicles are also banned.6Justia. Colorado Code 42-4-238 – Flashing Lights That covers aftermarket grille lights, strobe kits marketed for “security” use, and any decorative lighting that pulses.
The rationale is simple: another driver who sees flashing red or blue in the mirror assumes it’s law enforcement and may brake hard or pull over. Steady-burning accent lights in non-restricted colors are still permitted.
Trailer Lights
If you tow, the trailer needs its own working lights, and the federal baseline in FMVSS No. 108 applies in every state.
Every trailer needs two red taillights and two red stop lamps mounted between 15 and 72 inches above the road, two amber or red rear turn signals, and side marker lamps (amber on the front sides, red on the rear sides) mounted as far toward each end as practicable. Trailers roughly 80 inches or wider must also carry clearance lamps at the upper corners and three red identification lamps grouped near the top center of the rear. Trailers 30 feet or longer need intermediate side marker lamps near the midpoint of each side.7eCFR. 49 CFR 571.108 – Standard No. 108 Lamps, Reflective Devices, and Associated Equipment
Corrosion at the connector is the most common reason trailer lights stop working, especially on boat trailers that get dunked at launch ramps. Have someone stand behind the trailer while you cycle running lights, brakes, and both turn signals before every trip.
Penalties
Lighting violations in Colorado are traffic infractions rather than criminal offenses. Fines for a single defective headlight or taillight are modest, but they stack fast when an officer finds several problems in one stop. A vehicle with a burned headlight, a broken taillight, and a missing plate light can produce three separate citations at once.
The bigger cost is often secondary. An officer who stops you for a lighting defect now has a reason to look more closely at your license status, registration, and the rest of the vehicle. Insurers may nudge premiums after equipment citations appear on your record, though the effect is typically smaller than for a speeding ticket or at-fault crash.
Impersonating emergency lighting is treated far more seriously than a bulb-out. Using red, blue, or flashing lights in a way that mimics law enforcement or emergency vehicles can result in criminal charges rather than a traffic ticket.
How Enforcement Works
Colorado does not require annual safety inspections for privately owned passenger vehicles. The state runs an emissions program in the Denver metro area and North Front Range, but that program checks exhaust, not whether your brake lights work.8Department of Revenue – Motor Vehicle – Colorado DMV. Emissions Gasoline vehicles are exempt from emissions testing for the first seven model years, then tested every two years.9Colorado Department of Public Health and Environment. Emissions Inspections for Gasoline-Powered Vehicles
Because there’s no periodic safety check, lighting compliance is enforced almost entirely through traffic stops. An officer who spots a defective or non-compliant lamp can pull you over, issue a citation, or order immediate repairs. Keeping your lights working is on you.
Narrow Exceptions
Authorized emergency vehicles are exempt from the restrictions on red, blue, and flashing lights. Antique and collector vehicles registered under Colorado’s collector provisions can generally retain their original lighting systems rather than retrofit to modern standards, provided they still meet basic safety requirements.10Justia. Colorado Code 42-9-110 – Collector Vehicles Farm equipment traveling on public roads follows its own marking rules, most visibly the orange slow-moving vehicle triangle, plus flashing amber warning lamps and yellow reflectors on wider machines. None of these exceptions applies to an ordinary passenger vehicle on a daily commute.