Violation code

171.21B1

HM (General Requirements) - Failing to respond to an inquiry of an authorized representative or special agent of the USDOT, in conection with the study of incidents, within 30 days afters its receipt or within such other time as the inquiry may specify.

Hazardous Materials Compliance2Non-OOS· SMS Appendix A v3.20

171.21B1 is a HM Other violation under 49 CFR §171.21B1. It falls in the Hazardous Materials Compliance BASIC with a severity weight of 2/10.

Violation group: HM Other
Regulation §: 171.21B1
Severity weight: 2
Used in SMS: Yes
Status: Active
Updated: 5/15/2026

Last updated May 2026

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Notes

DSMS: Y | Comment: Added in 3.15 | Footnote: As of February 1, 2023, the violations in this table are included in SMS. Only violations cited on or after February 1 are included in SMS calculations. This update aligns SMS with how violations are being cited in a new software used for roadside inspections.

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Challenging 171.21B1 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 171.21B1 →Read the DataQs guide first

More codes in Hazardous Materials Compliance

Same BASIC category — ranked by national citation volume

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Codes under the same FMCSA violation group

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Frequently asked questions about 171.21B1

What does violation 171.21B1 mean?

171.21B1 is the FMCSA roadside-inspection violation code for "HM (General Requirements) - Failing to respond to an inquiry of an authorized representative or special agent of the USDOT, in conection with the study of incidents, within 30 days afters its receipt or within such other time as the inquiry may specify.", part of the HM Other group, cited under 49 CFR §171.21B1.

What BASIC does 171.21B1 affect?

171.21B1 falls under the Hazardous Materials Compliance BASIC in the FMCSA Safety Measurement System (SMS).

What is the CSA severity weight of 171.21B1?

171.21B1 carries a severity weight of 2 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 171.21B1 an out-of-service (OOS) violation?

No. 171.21B1 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 171.21B1 add to a carrier's score?

The point contribution of 171.21B1 depends on its severity weight (2/10) 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 171.21B1 be challenged through DataQs?

Yes. If you believe 171.21B1 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.

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CSA points calculator How to challenge a violation Draft a DataQs letter for 171.21B1 Hazardous Materials Compliance BASIC Carrier CSA lookup CSA glossary