What 393.11S means in plain language
FMCSR 393.11S targets commercial motor vehicles that hit the road without the required lighting equipment or reflectors in proper working order. In short, if your rig is missing lights that are supposed to be there, or if what's installed doesn't meet federal standards, an inspector can write you up under this code.
The "S" suffix distinguishes this as a specific sub-variant within the broader 393.11 lighting family of violations. The core issue is straightforward: every CMV is required to have specific lamps and reflective devices in specific locations, and operating without them — whether because a light burned out, a reflector got knocked off, or the equipment was never properly installed — puts you in violation.
This isn't about a light that's flickering or dim in a borderline way. The citation applies when required lighting devices or reflectors are inadequate or absent outright. A thorough pre-trip walk-around is your first and best defense.
What our enforcement data actually shows
Here's the first thing you need to understand if you just got cited: your truck almost certainly stays on the road. Across all-time inspection records in our database, 393.11S carries a 0.0% out-of-service rate — just 1 vehicle placed OOS out of 2,790 total citations. Compare that to the all-FMCSR average OOS rate of 31.4% across all codes, and it's clear that inspectors consistently treat this as a fix-it violation rather than a reason to park your truck.
That doesn't mean it's harmless. Our inspection records show 1,743 citations issued in the last 12 months alone, and 377 in just the last 90 days — so enforcement is active and accelerating. Across 13 million inspections, this code ranks #462 out of 3,036 FMCSR codes by total citation volume, putting it solidly in the top 15% of all cited violations. It's common enough that inspectors know exactly what to look for.
Looking at the monthly trend over the last 12 months, citation counts have been consistently high — ranging from 124 to 180 citations per month — with no meaningful seasonal dip. The 180 citations recorded in May 2025 represent the peak in that window. Enforcement isn't clustered in one period; inspectors are writing this code year-round.
Who gets cited most
Texas dominates the citation geography. Our data shows 778 citations in Texas alone over the last 180 days, with a 0.0% OOS rate. Iowa comes in second at 21 citations, also at 0.0% OOS. Illinois rounds out the top three with 7 citations. The OOS rates across all three states are identical — zero — so the primary consequence everywhere is the CSA record hit, not being sidelined.
The heavy concentration in Texas is consistent with the border-crossing traffic pattern visible in our carrier data. Our data shows fleets such as RUBEN CARLOS TREVINO SANCHEZ (USDOT 1649689) with 24 citations and TRANSPORTE INTERNACIONAL LOPEZ OCHOA SA DE C V (USDOT 1041907) with 15 citations leading all carriers in all-time 393.11S citations. Several other carriers in the top ten are also Mexico-domiciled operations, pointing to a pattern where cross-border equipment may face more scrutiny on lighting compliance at Texas inspection stations.
By vehicle make, Freightliner (FRHT) leads with 820 all-time citations under this code, followed by Kenworth (KW) at 445 and Peterbilt (PTRB) at 391. If you're running one of these platforms, inspectors are familiar with where lighting issues typically develop on your equipment.
How severe is this compared to similar codes
Within the Vehicle Maintenance category, 393.11S is a lower-stakes citation relative to some of its neighbors — but it doesn't exist in a vacuum.
The closest peer is 393.11 (Lighting devices/reflectors), which has accumulated 179,734 citations in our database with a 1.8% OOS rate. That broader code sees roughly 64 times the citation volume of 393.11S, which tells you that the "S" sub-variant is a narrower enforcement target. Still, a 1.8% OOS rate on the parent code means the underlying lighting deficiency can cross into OOS territory under certain conditions.
More telling is 393.9(a) (Inoperable required lamps), which carries a 15.4% OOS rate across 660,737 citations. That code addresses lamps that are present but not functioning — and it's far more likely to park your truck. The distinction matters: 393.11S is about devices that are missing or structurally inadequate, while 393.9(a) covers inoperability. An inspector can write both on the same inspection, and our data shows that 393.9 (a related variant) co-occurred with 393.11S in 201 shared inspections in the last 90 days alone.
For context on severity weighting, 393.11S carries a CSA Severity Weight of 3, which is on the lower end of the scale. It will appear in your CSA record, but it won't move the needle the way a brake or steering violation would.
How to avoid it
The co-occurring violation data tells a clear story: 393.11S rarely shows up alone. Use that pattern to build a sharper pre-trip routine.
- Walk every lamp location before you roll. With 393.9 (Inoperable Required Lamp) appearing in 201 shared inspections in the last 90 days, missing and inoperable lamps are almost always cited together. Check headlights, taillights, brake lights, turn signals, marker lights, and clearance lights — every one, every trip.
- Verify all reflectors are physically present and unobstructed. 393.11S specifically targets missing or inadequate reflective devices. After a load, after backing, or after any tight maneuver, confirm reflectors haven't been knocked off or covered.
- Check your coupling gear and trailer connection lighting. Our data shows 393.55E (Coupling device/towing methods defective) co-occurring in 93 shared inspections over 90 days. A rough hookup can damage rear lighting wiring or knock out a reflector.
- Carry spare bulbs and zip ties. If you're running a Freightliner, Kenworth, or Peterbilt — the three most-cited makes — know where your marker and clearance light assemblies are most vulnerable to vibration damage on your specific model.
- Pull your periodic inspection paperwork. 396.17C (No proof of periodic inspection) appeared in 91 shared inspections in the last 90 days. If an inspector finds a lighting deficiency, they will often look next at whether your annual inspection was done and documented. Have it in the cab.
- Check windshield condition while you're at it. 393.78 (Windshield condition defective) co-occurred in 96 shared inspections. Inspectors doing a thorough check on lighting often note windshield issues at the same time. One stop, multiple citations — avoid both.