390.21TB2DOT

390.21TB2DOT Violation: USDOT Number Not Displayed

A commercial motor vehicle was recorded as operating without the carrier’s USDOT number displayed as required.

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Plain-English answer

What does violation code 390.21TB2DOT mean?

A commercial motor vehicle was recorded as operating without the carrier’s USDOT number displayed as required.

Why carriers pay attention

How 390.21TB2DOT can affect a trucking safety record

Carrier-marking rules address the legal name or single trade name, USDOT number, legibility, contrast, and visibility from the required distance. Attribution errors can also put a record on the wrong carrier.

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 390.21TB2DOT inspection situations

  • The USDOT number is missing, obscured, too small, low-contrast, or displayed under another carrier.

  • A leased or recently transferred vehicle still shows outdated carrier markings.

DataQ review

When a 390.21TB2DOT 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 correct USDOT number was displayed legibly on both sides at inspection.
  • The vehicle was operating under a different responsible carrier documented by the lease and trip records.
  • The inspector recorded the wrong USDOT number or vehicle.

Evidence to collect

  • Time-stamped photographs of both sides of the power unit
  • Lease, dispatch, and operating-authority records for the trip
  • Registration, VIN, and unit records connecting the vehicle to the carrier
Compliance expert review

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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

390.21TB2DOT violation FAQ

What does a 390.21TB2DOT violation mean?

A commercial motor vehicle was recorded as operating without the carrier’s USDOT number displayed as required.

Which FMCSA SMS BASIC is associated with 390.21TB2DOT?

The inspection record should be checked to determine whether and how code 390.21TB2DOT is used in FMCSA Safety Measurement System calculations.

Can a trucking company challenge a 390.21TB2DOT 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 390.21TB2DOT finding was wrong.

What evidence helps review a 390.21TB2DOT violation?

Useful evidence may include time-stamped photographs of both sides of the power unit, lease, dispatch, and operating-authority records for the trip, registration, vin, and unit records connecting the vehicle to the carrier. The best evidence is tied to the cited vehicle, driver, location, and inspection time.

Keep reviewing

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Source references: 49 CFR 390.21 and FMCSA roadside inspection data. This guide is general information and does not guarantee a DataQs outcome or replace legal advice.