What 393.17B means in plain language
FMCSR 393.17B addresses lamps and reflectors on your commercial motor vehicle. The regulation requires that your truck's lighting and reflective equipment meet federal standards. This includes headlights, taillights, clearance lights, reflectors, and any other lighting device that FMCSA regulations specify for your vehicle type and configuration.
When an inspector cites you for 393.17B, they've found that your lamps or reflectors do not meet those requirements. This might mean a light is broken or missing, a reflector is damaged or obscured, or a lighting system isn't functioning as designed. It's a defect that's safety-critical: other drivers and pedestrians depend on your vehicle being visible, especially in low-light conditions.
Unlike some maintenance violations that allow you to continue operating under certain conditions, this one is treated very seriously in the field. The sheer frequency with which 393.17B violations result in an out-of-service order tells you how inspectors prioritize lighting safety.
What our enforcement data actually shows
Across our 13 million+ roadside inspection records, we've logged 108 total citations for 393.17B. In the last 12 months, that's 40 citations, and in the most recent 90 days, 12 citations. The code is ranked #1395 out of 3,036 FMCSR codes by citation volume, making it a relatively uncommon violation overall.
However, the severity is undeniable. Of the 108 all-time citations in our database, 99 resulted in an out-of-service order—a 91.7% rate. That is dramatically higher than the all-FMCSR average OOS rate of 31.4%. Only 9 of the 108 citations allowed the driver to continue operating. This disparity means that when an inspector finds inadequate lamps or reflectors, they almost always take the vehicle out of service on the spot.
Recent months show volatility. February 2026 saw 9 citations (8 OOS), while April, July, and November 2025 each saw only 1–2 citations. May and June 2025, and October 2025, each produced 5–6 citations. This suggests 393.17B violations cluster seasonally or regionally rather than occurring uniformly throughout the year.
Who gets cited most
Texas leads in 393.17B citations over the last 180 days with 8, of which 7 resulted in out-of-service orders (87.5% rate). Illinois and North Carolina follow with 3 citations each; both states saw a 100% out-of-service rate on their citations. Pennsylvania also recorded 3 citations but with a lower 66.7% OOS rate—the only top state that deviated significantly from the near-universal out-of-service pattern.
Our data shows specific fleets have encountered this violation more than once. Brookfield Auto Body Inc (USDOT 2923904) and Copart Catastrophe Response Fleet LLC (USDOT 2869944) each appear in our records with 4 citations for 393.17B. Windy City Towing Inc (USDOT 395112) has 3 on record. These numbers don't indicate a pattern of negligence—towing and catastrophe-response operations inherently work with older or recently damaged vehicles where lighting defects are more likely to surface.
How severe is this compared to similar codes
Within the Vehicle Maintenance category, 393.17B sits on the extreme end of the severity spectrum. Consider its peer codes:
393.9(a) — Inoperable required lamps has 660,737 citations with a 15.4% OOS rate. Despite vastly higher citation volume, it results in out-of-service far less often than 393.17B.
393.11 — Lighting devices/reflectors totals 179,734 citations with only a 1.8% OOS rate. This is a closely related code addressing similar equipment, yet it almost never triggers an out-of-service order.
396.3(a)(1) — Inspection/repair/maintenance general has 236,919 citations with a 45.3% OOS rate—still half the rate of 393.17B.
The contrast is striking. 393.17B's 91.7% out-of-service rate and its CSA severity weight of 3 tell inspectors that inadequate lamps and reflectors warrant immediate vehicle removal from service. This is not a "fix it within 24 hours" violation.
How to avoid it
Lighting defects don't appear overnight. Prevention starts with your pre-trip inspection.
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Walk your entire vehicle in daylight and dusk. Check every light: headlights (both high and low beam), parking lights, turn signals, marker lights (amber on the side, red on the rear), brake lights, backup lights, and clearance lights. If your truck is longer than 30 feet or has trailers, verify all required lights on each unit.
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Clean and secure all reflectors. Mud, salt, and road grime obscure reflective surfaces. Wipe them down during pre-trip. Check that no reflectors are cracked, peeling, or missing their backing.
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Test lights at night or in a dock. Your parking lot during daylight won't reveal a dim or inoperable bulb. Back into a loading dock or ask a colleague to watch your lights while you cycle through each function: parking, headlight, high beam, turn signals left and right, brake, and reverse.
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Replace bulbs and fixtures before they fail completely. If a light is dim or flickering, replace it immediately. Don't wait for an inspection to fail it.
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Address structural damage promptly. Our data shows that fifth-wheel defects co-occur with 393.17B violations in 4 recent inspections. When your vehicle sustains impact damage—even minor—inspect all nearby lighting and reflectors. A collision that damages a frame rail or fifth wheel often knocks out marker lights or reflectors in the vicinity.
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Check your specific vehicle's lighting requirements. Different makes—Freightliner, Ford, International, Chevrolet, and Ram dominate our citation records—have varying light configurations. Consult your truck's manual or the FMCSA's lighting diagrams to ensure you know what your vehicle must have.
Our inspection records show that lighting violations are nearly guaranteed to result in an out-of-service order. A failed pre-trip inspection by an FMCSA officer will strand you. Taking 15 minutes before each shift to walk your truck and check every light is your cheapest insurance.