393.9

393.9 Violation: Inoperable Required Lamp

A lamp required by the Federal Motor Carrier Safety Regulations was recorded as missing, damaged, or not operating when inspected.

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Plain-English answer

What does violation code 393.9 mean?

A lamp required by the Federal Motor Carrier Safety Regulations was recorded as missing, damaged, or not operating when inspected.

Why carriers pay attention

How 393.9 can affect a trucking safety record

Lighting violations can affect a trucking company’s Vehicle Maintenance BASIC and may create an out-of-service condition depending on the lamp, operating conditions, and applicable CVSA criteria.

FMCSA inspection data can flow into the Safety Measurement System used to organize carrier performance into Behavior Analysis and Safety Improvement Categories, commonly called FMCSA SMS BASICs. The carrier should verify the inspection, the assigned BASIC, and whether the violation is included in the official calculation.

How it gets cited

Common 393.9 inspection situations

  • A required headlamp, tail lamp, stop lamp, turn signal, or identification lamp does not illuminate.

  • The inspection report uses a general lamp code even though a more specific lighting code may describe the condition.

DataQ review

When a 393.9 violation may deserve a closer look

A DataQ challenge should identify a specific factual or legal error in the inspection data. These are review questions—not assumptions that the violation should be removed.

Potential review angles

  • The cited lamp was not required for that vehicle configuration or operating condition.
  • The report identifies the wrong unit, lamp position, or violation code.
  • Contemporaneous evidence shows the lamp operated at the time of inspection.

Evidence to collect

  • Time-stamped inspection-lane photographs or video
  • Repair orders and technician findings tied to the cited unit
  • The complete roadside inspection report and vehicle configuration
Compliance expert review

Not sure whether 393.9 belongs on your record?

We'll review the violation details, identify evidence gaps, and explain whether the facts may support a DataQ challenge.

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DataQs changes in 2026

A stronger review process still requires a stronger record.

FMCSA’s 2026 DataQs overhaul adds independent review stages, decision deadlines, and more detailed explanations. Carriers still carry the burden of identifying the error and supporting the requested correction.

See the 2026 DataQs changes
Frequently asked questions

393.9 violation FAQ

What does a 393.9 violation mean?

A lamp required by the Federal Motor Carrier Safety Regulations was recorded as missing, damaged, or not operating when inspected.

Which FMCSA SMS BASIC is associated with 393.9?

Code 393.9 is commonly associated with the Vehicle Maintenance BASIC in the FMCSA Safety Measurement System. Inclusion and weighting should be confirmed on the carrier’s official record.

Can a trucking company challenge a 393.9 violation?

A carrier may submit an FMCSA DataQs Request for Data Review when the underlying inspection data is incomplete or incorrect. A repair made after the inspection does not by itself prove the original 393.9 finding was wrong.

What evidence helps review a 393.9 violation?

Useful evidence may include time-stamped inspection-lane photographs or video, repair orders and technician findings tied to the cited unit, the complete roadside inspection report and vehicle configuration. The best evidence is tied to the cited vehicle, driver, location, and inspection time.

Keep reviewing

Related DOT violation codes

View all violation guides
393.11Required Lamps and Reflective MaterialLighting393.9BRKLAMPInoperative Brake LampsLighting396.17CNo Proof of Periodic InspectionInspection and maintenance393.75A3Flat Tire or Audible Air LeakTires and wheels

Source references: 49 CFR 393.9 and FMCSA roadside inspection data. This guide is general information and does not guarantee a DataQs outcome or replace legal advice.