Violation code

172.502(a)(1)

Prohibited placarding

Hazardous Materials Compliance5Non-OOS· SMS Appendix A v3.20

172.502(a)(1) is a Markings - HM violation under 49 CFR §172.502(a)(1). It falls in the Hazardous Materials Compliance BASIC with a severity weight of 5/10. Nationally it was cited 5,514 times in the last five years, with an OOS rate of 19.3%.

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National roadside inspection stats

as of 6/20/2026

Inspections

5,442

that found this code

Violations

5,514

total written

OOS rate

19.3%

1,065 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.

Violation group: Markings - HM
Regulation §: 172.502(a)(1)
Severity weight: 5
Used in SMS: Yes
Status: Active
Updated: 6/20/2026

Last updated June 2026

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Notes

DSMS: N

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Challenging 172.502(a)(1) through FMCSA DataQs

If this violation was written incorrectly, here are the angles trucking-safety managers use to contest it. Playbook: Hazardous Materials.

Common ways to challenge this code

Shipment was not placardable
The materials transported did not exceed the threshold quantities requiring placards under 49 CFR Part 172 Subpart F.
Evidence that wins
- ✓Shipping papers showing UN number, hazard class, and quantity
- ✓Manufacturer's product specification sheet
Administrative HazMat code (not in SMS)
This administrative code is on the inspection report but does not contribute to CSA BASIC scoring per FMCSA SMS Methodology Appendix A.
Evidence that wins
- ✓FMCSA SMS Methodology Appendix A reference

Common pitfalls — avoid these

⚠Administrative HazMat codes still appear on the PSP record even when not scored in SMS

⚡ Draft a challenge for 172.502(a)(1) →Read the DataQs guide first

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Other Markings - HM codes

Codes under the same FMCSA violation group

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Frequently asked questions about 172.502(a)(1)

What does violation 172.502(a)(1) mean?

172.502(a)(1) is the FMCSA roadside-inspection violation code for "Prohibited placarding", part of the Markings - HM group, cited under 49 CFR §172.502(a)(1).

What BASIC does 172.502(a)(1) affect?

172.502(a)(1) falls under the Hazardous Materials Compliance BASIC in the FMCSA Safety Measurement System (SMS).

What is the CSA severity weight of 172.502(a)(1)?

172.502(a)(1) carries a severity weight of 5 out of 10. Higher weights indicate violations more closely tied to crash risk, and they count more toward a carrier's Hazardous Materials Compliance score.

Is 172.502(a)(1) an out-of-service (OOS) violation?

No. 172.502(a)(1) is not an out-of-service violation, so on its own it does not trigger an out-of-service order at the roadside.

How many CSA points does 172.502(a)(1) add to a carrier's score?

The point contribution of 172.502(a)(1) depends on its severity weight (5/10) multiplied by a time weight of 3, 2, or 1 based on how recent the inspection is. You can calculate the exact contribution with the CSA points calculator.

Can 172.502(a)(1) be challenged through DataQs?

Yes. If you believe 172.502(a)(1) 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 172.502(a)(1)Hazardous Materials Compliance BASIC Carrier CSA lookup CSA glossary