What 393.17 means in plain language
FMCSR 393.17 covers the lighting and reflector systems on your commercial motor vehicle. This code is enforced when your truck's lamps or reflectors do not meet federal requirements—either they're missing, inoperable, the wrong color, positioned incorrectly, or not maintained to standard.
Inspectors check that all required lights are present and functional: headlamps, tail lamps, turn signals, marker lights, and reflectors. These systems are safety-critical because they make your truck visible to other drivers, especially at night or in poor weather. The regulation exists to prevent collisions caused by inadequate visibility.
If you were cited for 393.17, the inspector found one or more lamps or reflectors on your vehicle that failed to meet these standards during a roadside inspection.
What our enforcement data actually shows
Across our 13 million+ inspection records, 393.17 has been cited 258 times all-time. In the last 12 months, we recorded 7 citations; in the last 90 days, just 1 citation. This makes 393.17 ranked #1137 out of 3,036 FMCSR codes by citation volume—a relatively uncommon violation.
However, when this code is cited, enforcement is strict. Our data shows an out-of-service (OOS) rate of 87.2%: inspectors placed 225 vehicles out of service and did not place 33 out of service. This is substantially higher than the all-FMCSR average OOS rate of 31.4%. In other words, when inspectors cite 393.17, they are far more likely to deem the vehicle unsafe to operate than they are for most other violations.
The CSA severity weight assigned to this code is 3, reflecting its importance in the Compliance, Safety, and Accountability program.
Who gets cited most
Over the last 180 days, citations for 393.17 appeared in two states. North Carolina had 1 citation with a 100.0% out-of-service rate (1 OOS, 0 not OOS). Texas had 1 citation with a 0.0% out-of-service rate (0 OOS, 1 not OOS). This variation reflects the small sample size in the recent window, but shows that enforcement outcomes can differ by jurisdiction.
Across all-time records, our data shows fleets such as COPART CATASTROPHE RESPONSE FLEET LLC with 4 citations for this code, and K & D TOWING SERVICE INC with 3 citations. Neither pattern suggests systemic non-compliance; these are absolute counts from a relatively rare violation.
How severe is this compared to similar codes
Within the vehicle maintenance category, 393.17 sits among other lighting and inspection-related codes. Here's how it compares:
393.9(a) — Inoperable required lamps has been cited 660,737 times with a 15.4% OOS rate. This code is far more common and results in out-of-service fewer times proportionally.
393.11 — Lighting devices/reflectors has 179,734 citations with a 1.8% OOS rate. Despite covering similar equipment, it is cited far more often but rarely results in out-of-service placement.
396.3(a)(1) — Inspection/repair/maintenance general has 236,919 citations with a 45.3% OOS rate. While also in the maintenance category, it is cited more frequently and has a lower OOS rate than 393.17.
The contrast is striking: 393.17 is rare but carries one of the highest OOS rates in its peer group. When an inspector cites inadequate lamps or reflectors under this specific code, they are signaling a serious deficiency.
How to avoid it
To avoid a 393.17 citation, conduct these pre-trip and periodic checks:
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Walk around your vehicle before every trip. Check all headlamps, tail lamps, brake lights, turn signals, and side marker lights. Activate each circuit and confirm lights illuminate. Look for cracks, moisture, or discoloration in lens covers.
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Inspect reflectors for damage and cleanliness. Reflectors lose effectiveness when dirty or corroded. Wipe them clean and check for impact damage. Replace any reflector that is cracked, faded, or missing.
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Test lights with the engine running and off. Some wiring issues only appear under load. Turn on your headlamps, brakes, and turn signals with the engine idling and also with it off to catch intermittent failures.
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Check mounting hardware and alignment. Lamps that hang loose or point in the wrong direction can fail inspection. Verify all lamp housings are securely fastened and aimed correctly.
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Monitor vehicle-specific wear patterns. Our data shows citations affecting Ford (23 citations) and International (20 citations) trucks more frequently. If you operate one of these makes, plan more frequent electrical system reviews.
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Address co-occurring defects promptly. In recent inspections, 393.17 has appeared alongside 393.71H10 (fifth wheel defective). Do not delay repairs on one system while another system has a known fault; inspectors often cite multiple failures in a single stop.
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Keep spare bulbs, fuses, and reflectors on board. If you discover a burned-out bulb or cracked reflector during your pre-trip, replace it immediately rather than proceeding with a known defect.