DOT violations › 393.9
FMCSA Violation 393.9: Inoperative required lamps
Cited when required lamps (headlamps, tail, brake, turn, marker) are inoperative. Common, often easy to repair.
Last updated: June 2026 · Data sources: NHTSA vPIC (live) and FMCSA public inspection records (periodic refresh).
Quick answer
FMCSA roadside violation 393.9 (inoperative required lamps) is a lighting citation that rarely results in an out-of-service order. On a used truck, a past 393.9 citation does not prove a current defect — it tells you exactly what to verify before you buy. If the VIN appears in FMCSA roadside records, TruckWhere shows whether it has this or other violations.
Free FMCSA roadside summary. We accept exact 17-character VINs only and never silently correct a VIN.
Is 393.9 serious?
This is a Lighting violation. It rarely results in an out-of-service order. An out-of-service order means the vehicle could not continue until the condition was corrected at that time — it does not prove the defect remains today.
What a buyer should ask the seller
Ask whether the lighting fault was wiring, bulbs, or connectors, and if it was fully repaired.
What a mechanic should inspect
Verify all required lamps function; check grounds, connectors, and harness condition.
How 393.9 appears in a TruckWhere report
In a TruckWhere DOT Buyer Report, a 393.9 citation shows up in the roadside timeline with its date, state, unit attribution, out-of-service status, and a plain-English explanation — plus a Lighting entry in repeated-system detection if it occurred more than once.
Check a VIN for 393.9 →Related lighting violations
Learn more
Frequently asked questions
- What does FMCSA violation 393.9 mean?
- Cited when required lamps (headlamps, tail, brake, turn, marker) are inoperative. Common, often easy to repair. It rarely results in an out-of-service order.
- Is violation 393.9 serious?
- It is a lighting citation that rarely results in an out-of-service order. Historical violations do not prove a current defect, but they tell you exactly what to verify before buying.
- Can I check if a truck's VIN has violation 393.9?
- Yes — if the VIN appears in FMCSA roadside records, TruckWhere shows its violations (including codes like 393.9), out-of-service events, and the inspection timeline for that exact VIN.