Violation code

390.21B

Carrier name and/or USDOT Number not displayed as required

Not in SMSOOS· FMCSA A&I All Violations

390.21B is a Other violation under 49 CFR §390.21B. It is an out-of-service violation; it is not scored in the SMS. Nationally it was cited 39,160 times in the last five years, with an OOS rate of 0.0%.

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National roadside inspection stats

as of 9/20/2026

Inspections

38,646

that found this code

Violations

39,160

total written

OOS rate

0.0%

6 OOS

Source: FMCSA roadside inspection data (last 5 years). The OOS rate is the share of these violations that led the officer to mark the driver or vehicle out of service.

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Not used in SMS BASIC scoring

Recorded on your inspection report and visible on the PSP, but contributes 0 points to CSA BASIC scores — even if cited Out-of-Service.

Violation group: Other
Regulation §: 390.21B
Severity weight: N/A
Used in SMS: No
Status: Active
Updated: 9/20/2026

Last updated September 2026

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What 390.21B means — and how to avoid it

In plain English

In plain terms, 390.21B is cited for carrier name and/or USDOT Number not displayed as required. It falls under the FMCSA rules on general FMCSR compliance and marking. Because it’s an out-of-service condition, an inspector can put the driver or vehicle out of service on the spot until it’s corrected.

What the inspector checks

•Required markings/USDOT number and general compliance items

How to prevent it

✓Keep registration, marking, and required records current

How it affects your CSA

0 CSA points

390.21B is not scored in the SMS. It adds 0 CSA points — even if written out-of-service — but it still appears on the inspection report and the driver’s PSP.

General guidance from the violation’s FMCSA classification — not legal advice, and not a substitute for the inspector’s findings or 49 CFR.

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Challenging 390.21B through FMCSA DataQs

If this violation was written incorrectly, here are the angles trucking-safety managers use to contest it. Playbook: Codes not used in SMS scoring.

Common ways to challenge this code

Not used in SMS — should not affect BASIC
This code is on the inspection report but is excluded from SMS BASIC scoring per Appendix A. Use DataQs to correct the underlying data quality issue if the code was written in error, but understand it does not affect the CSA percentile.
Evidence that wins
- ✓FMCSA SMS Methodology Appendix A reference
- ✓Underlying inspection report

Common pitfalls — avoid these

⚠These codes still appear on PSP — challenge the data if the cite was wrong

⚡ Draft a challenge for 390.21B →Read the DataQs guide first

Other Other codes

Codes under the same FMCSA violation group

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Frequently asked questions about 390.21B

What does violation 390.21B mean?

390.21B is the FMCSA roadside-inspection violation code for "Carrier name and/or USDOT Number not displayed as required", part of the Other group, cited under 49 CFR §390.21B.

What BASIC does 390.21B affect?

390.21B is not scored in any CSA BASIC. It is recorded on the inspection report and appears on the PSP, but it contributes 0 points to a carrier's SMS BASIC percentiles.

Is 390.21B an out-of-service (OOS) violation?

Yes. 390.21B is an out-of-service violation, meaning the driver or vehicle can be placed out of service at the roadside until the issue is corrected. OOS violations also add an extra severity point in SMS scoring.

How many CSA points does 390.21B add?

390.21B adds 0 CSA points because it is not used in SMS scoring, even when written out of service.

How can a driver prevent 390.21B?

Keep registration, marking, and required records current.

Can 390.21B be challenged through DataQs?

Yes. If you believe 390.21B was recorded in error, you can file a Request for Data Review (RDR) through the FMCSA DataQs system with supporting evidence. A successful challenge can remove or correct the violation on your record.

Keep going

CSA points calculator How to challenge a violation Draft a DataQs letter for 390.21B Carrier CSA lookup CSA glossary

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