Direct answers on 390.21(c) enforcement, out-of-service risk, what to do after citation, and state-by-state data from 13M+ roadside inspections.
Ranks #564 of 3,146 FMCSR codes by citation frequency • OOS rate of 0.1% is below the FMCSR-wide average of 33.3%.
Improper size, location, or color of CMV marking
Direct answers grounded in TruckCodex inspection data
No. Across our inspection records, 390.21(c) resulted in an out-of-service placement in only 1 case out of 1,824 all-time citations—a 0.1% OOS rate. This is dramatically lower than the 31.4% all-FMCSR average OOS rate. You will almost certainly be allowed to continue operating, though you must correct the violation within the timeframe the inspector provides.
390.21(c) is ranked #554 out of 3,036 FMCSR codes by citation frequency, placing it in the lower-volume tier. Its 0.1% OOS rate sits far below peer codes in the General/Admin category—codes like 390.21TB2-DOT (74,663 citations, 0.0% OOS) and 390.21T(b) (61,097 citations, 0.0% OOS) show the same lenient enforcement posture. This is an administrative citation, not a safety defect.
First, document the inspector's written correction deadline. Second, inspect your vehicle for the specific 390.21(c) issue noted in the citation. In our last 90 days of data, 390.21(c) most often appears alongside inoperable lamps (393.9—31 shared inspections) and brake issues (393.47E, defective slack adjusters—17 shared inspections). Check those systems even if not cited. Third, photograph compliance once corrected and keep records. Submit proof of correction to your state motor carrier office before the deadline.
Texas dominates enforcement of this code. In the last 180 days, Texas accounted for 190 citations—far above any other state. New Mexico follows with 14 citations, and North Carolina with 9. All three states show 0% OOS rates, consistent with the national pattern. If you operate in Texas, be especially attentive to compliance.
Citations remain steady and low. Over the last 12 months, 390.21(c) citations averaged about 40 per month, peaking in July 2025 at 62 citations and dropping to 12 in April 2025. In the last 90 days, we recorded 98 citations across all 13 million+ inspections in our database—a minor fraction of total enforcement activity. No upward trend suggests this is not becoming a compliance hot-spot.
Yes, you can file a DataQs (Roadside Inspection Data Quality) appeal if you believe the citation was issued in error. 390.21(c) is typically a documentation or marking issue. If you can prove you met the requirement at the time of inspection (e.g., records, photos, witness), FMCSA may remove the citation from your CSA record. File within 90 days of the inspection. Contact your carrier's compliance department or a motor carrier attorney for help with the appeal.
Freightliners lead by far: 272 citations in our all-time data. Kenworths follow with 187 citations, and Peterbilts with 160. These three manufacturers account for over half of all 390.21(c) citations, likely because they are the most common heavy-duty units on the road. Vehicle make does not indicate higher violation risk—it reflects market share.
Autolineas Perza SA de CV (USDOT 3346939) has the highest count at 14 all-time citations. Rosdel Logistic SA de CV follows with 7. However, citation frequency is a function of fleet size and inspection exposure; a carrier with more vehicles and inspections will naturally accumulate more citations. Compare violation rate (citations per inspection) rather than raw count when assessing carrier safety culture.
Where 390.21(c) is most commonly cited (last 180 days)
Other violations commonly found on the same inspection (last 90 days)
TruckCodex aggregates official public-sector datasets. See the Source registry for dataset-level coverage and the Freshness log for last-import timestamps.
Census, SAFER, SMS, Licensing & Insurance (L&I), roadside inspections, crashes, and authority history.
Vehicle recall campaigns, defect investigations, and consumer safety complaints (SCRS).
Cross-border carrier registry and Canadian recall campaigns where applicable.
TruckCodex is an independent aggregator; it is not affiliated with FMCSA, NHTSA, EIA, or Transport Canada. Always verify compliance-critical information directly with the originating agency.