What 393.9A-LPL means in plain language
This violation is issued when a commercial motor vehicle is driven on public roads while one or more of its required lamps are not functioning. The key word here is required — federal regulations mandate specific lamps be operational at all times, and if an inspector finds any of them dark, burned out, or otherwise non-functional, you get written up under this code.
The "LPL" suffix is one of several sub-codes grouped under the broader 393.9A family, each targeting a specific lamp type or configuration. You may have been cited for a parking lamp, a position lamp, or a similar required lighting device that failed to illuminate during the inspection. The inspector doesn't need to prove intent — if the lamp doesn't work, the citation is issued.
The practical takeaway: this is a lights-out citation. It is entirely preventable with a thorough pre-trip inspection, and the data backs that up — virtually every driver cited for this code kept driving.
What our enforcement data actually shows
Across our database of 13 million+ inspections, 393.9A-LPL has generated 2,422 all-time citations, placing it at #496 out of 3,036 FMCSR codes by citation volume. That puts it squarely in the upper quartile of enforcement frequency — this is not a rarely-enforced technicality.
Enforcement is clearly accelerating. In the last 12 months alone, 1,462 citations were issued under this code — that's more than 60% of the entire all-time total recorded in our database. In just the last 90 days, officers issued 288 citations. Looking at the monthly trend, volume spiked from 53 citations in April 2025 to a peak of 156 in July 2025, and has remained consistently elevated, with 140 citations in February 2026 and 110 in March 2026.
Now the part that should immediately reduce your stress level: the out-of-service rate for 393.9A-LPL is 0.1%. Out of 2,422 all-time citations, only 2 drivers were placed out of service. The other 2,420 were cited and allowed to continue. For context, the all-FMCSR average OOS rate across all codes in our database is 31.4% — 393.9A-LPL comes in at a fraction of that. This code is flagged as OOS-ineligible, meaning inspectors are not authorized to park your truck for this violation alone under standard enforcement guidelines.
What this means for you today: you received a citation and a CSA severity weight of 3 will be attached to your record, but you were almost certainly not parked. The real consequence is the mark on your Safety Measurement System (SMS) profile and your carrier's BASIC scores.
Who gets cited most
Our inspection records show that enforcement is concentrated in a handful of states. Over the last 180 days, the top three states by citation count were US federal jurisdictions or border crossings (74 citations), New York (62 citations), and Pennsylvania (52 citations). Arizona followed with 42 citations, and Kentucky rounded out the top five with 36 citations.
None of the top ten states recorded a single OOS placement during this period — every one of them sits at a 0.0% OOS rate for 393.9A-LPL. There is no meaningful OOS-rate variation across these states because the floor is zero across the board.
On the carrier side, our data shows fleets such as RIO BRAVO TRUCKING SA DE CV (USDOT 1099727) with 8 all-time citations and JULIO CESAR CIENFUEGOS GARZA (USDOT 2389566) with 6 citations appearing at the top of the citation counts. The presence of several cross-border carriers in the top list aligns with the heavy enforcement activity recorded at federal inspection points.
How severe is this compared to similar codes
To put 393.9A-LPL in context, consider how it compares to peer codes in the Vehicle Maintenance category.
The broadest parent code, 393.9(a) — Inoperable required lamps, has accumulated 660,737 citations in our database with a 15.4% OOS rate. That OOS rate is dramatically higher than the 0.1% seen for 393.9A-LPL, which tells you that the specific lamp type or configuration captured by this sub-code is treated as far less safety-critical by inspectors in practice.
396.3(a)(1) — Inspection/repair/maintenance (general) shows 236,919 citations and a 45.3% OOS rate — one of the more aggressive OOS rates in the category. If your lamp failure is discovered alongside a broader maintenance deficiency, the overall inspection outcome changes significantly.
396.17C-PI — No proof of periodic inspection sits at 212,081 citations with a 0.0% OOS rate, making it the closest behavioral analog to 393.9A-LPL in terms of enforcement consequence. Both codes add CSA weight without parking your truck, but both are the kind of repeat violations that erode a carrier's BASIC scores over time.
How to avoid it
The co-occurring violation pattern in our 90-day data is the clearest roadmap for prevention. In the same inspections where 393.9A-LPL was cited, officers also frequently wrote up other lamp-related sub-codes — 393.9A-LFTSI (56 shared inspections), 393.9A-LIL (49 shared inspections), 393.9A-LSLI (36 shared inspections), 393.9A-LCL and 393.9A-LSML (32 each). That pattern says one thing clearly: when one lamp is out, inspectors are finding multiple lamps out on the same truck.
Here is what you can do before and during every pre-trip to break that pattern:
- Walk every light on the truck — individually. Don't assume a lamp works because it worked yesterday. Freightliner leads all-time citations with 439, followed by Kenworth at 210 and International at 172. These are high-frequency trucks on the road, and vibration, moisture intrusion, and corroded sockets are common across all platforms. Each lamp gets a visual confirmation.
- Check parking lamps and position lamps specifically. The LPL sub-code targets this lamp family. Activate them separately from your headlamps during your pre-trip walk-around and confirm illumination at each corner of the vehicle.
- Inspect your trailer lighting connections. Wabash National trailers appear in the top vehicle makes with 101 citations. Pigtail connections and seven-way plug contacts corrode, and a loose or dirty connection can kill a lamp circuit without any obvious physical damage.
- Carry spare bulbs and fuses. A burned-out lamp you can fix in the lot is a citation you never receive. Keep a basic lamp kit — replacement bulbs for common positions, spare fuses, and dielectric grease for connections — in your cab.
- Cross-reference your inspection against the other co-occurring codes. In the same 90-day window, 396.17C-PI (no proof of periodic inspection) appeared in 54 shared inspections alongside 393.9A-LPL, and tire violations appeared in 41. If your lamp maintenance is slipping, other maintenance items are likely slipping too. A complete pre-trip — not a quick walk-by — is the only reliable defense.