What 390.21T(f) means in plain language
390.21T(f) is a marking and identification requirement under FMCSR Part 390. The regulation concerns how your commercial motor vehicle must display specific information to comply with federal safety standards. This is an administrative compliance issue—inspectors are checking that your vehicle meets labeling and marking standards during a roadside inspection.
The violation is cited when an inspector finds that your vehicle lacks proper marking, display, or identification in the location or format required by federal rules. Unlike mechanical defects, this is purely a paperwork and label compliance matter. It doesn't involve safety equipment failure; it's about whether the required information is visible and correctly placed.
What our enforcement data actually shows
Across our 13 million inspection records, 390.21T(f) has been cited 204 times in all-time data, with zero citations in the last 12 months and zero in the last 90 days. This code ranks #1208 of 3,036 FMCSR codes by citation volume, making it one of the least-cited violations nationwide.
The out-of-service rate for 390.21T(f) is 0.0%—all 204 citations resulted in the driver being allowed to continue. This is well below the all-FMCSR average out-of-service rate of 31.4%, indicating that inspectors view this violation as correctable at the roadside rather than an immediate safety threat requiring vehicle removal.
The fact that this code has not been cited in the last 12 months suggests either improved compliance across the industry or a shift in enforcement priorities toward more critical violations.
Who gets cited most
Our inspection records don't identify the top three states for this specific code due to limited citation volume. However, we do see concentration among carrier fleets. DRIVERDO LLC (USDOT 2841522) leads with 11 citations, followed by NORTON TRANSPORT INC (USDOT 925129) with 10 citations. These numbers should not be interpreted as indicating systemic negligence—they reflect the volume of inspections these larger fleets undergo and the frequency with which their vehicles encounter roadside checkpoints.
Vehicles cited for 390.21T(f) span diverse makes. Freightliner trucks (FRHT) account for 18 of the 204 all-time citations, followed by Peterbilt (PTRB) with 8 and Ford with 7. This distribution mirrors the overall composition of the commercial fleet and does not suggest that any particular manufacturer's vehicles are inherently non-compliant.
How severe is this compared to similar codes
390.21T(f) sits within the General/Admin category. Peer codes in the same category show vastly higher citation volumes:
- 390.21TB2-DOT: 74,663 citations, 0.0% OOS rate
- 390.21T(b): 61,097 citations, 0.0% OOS rate
- 390.21TB1-MC: 59,189 citations, 0.0% OOS rate
These related marking and identification violations are cited far more frequently, suggesting that 390.21T(f) captures a narrower subset of marking violations. The 0.0% OOS rate is consistent across all these codes, confirming that marking violations are treated as administrative correctable issues rather than safety defects.
Other peer codes like 390.21(a) (Vehicle marking requirements) have been cited 25,872 times with 0.0% OOS rate, and 390.21(b) (USDOT number not displayed) has 13,244 citations also at 0.0% OOS. The pattern is clear: marking and identification codes are low-severity and non-OOS violations across the board.
How to avoid it
Since this code has not been cited in the last 12 months and carries zero out-of-service risk, compliance is straightforward and highly achievable:
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Verify all required markings before each trip. Conduct a pre-trip walk-around and confirm that your vehicle displays all federally required identification information in the correct locations. Check that nothing is obscured, faded, or missing.
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Know your vehicle's specific marking requirements. Different vehicle types and configurations may have different marking standards. Review your company's vehicle documentation or ask your dispatcher if you're unsure what markings apply to your specific truck or trailer.
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Keep marking information legible and secure. Ensure that placards, labels, and identification numbers are not peeling, faded, or damaged. Replace any that have degraded since your last inspection.
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Document compliance at pre-trip. Many carriers require drivers to sign off on a pre-trip checklist that includes marking verification. This protects you and creates a record of due diligence.
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Report missing or damaged markings immediately. If you notice during a pre-trip that a required marking is missing or damaged, report it to maintenance or dispatch rather than taking the vehicle out. A roadside citation is avoidable with proactive reporting.
Because this violation carries zero out-of-service consequences and is purely administrative, it is entirely within your control to prevent through careful pre-trip inspection and attention to detail.