Violation code

177.840G-HMHC

HM (Highway Carriage) - Liquid discharge valve not closed during the transportation of Class 2 hazardous materials.

Hazardous Materials Compliance4Non-OOS· SMS Appendix A v3.20

177.840G-HMHC is a Cargo Protection - HM violation under 49 CFR §177.840G-HMHC. It falls in the Hazardous Materials Compliance BASIC with a severity weight of 4/10. Nationally it was cited 61 times in the last five years, with an OOS rate of 11.5%.

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National roadside inspection stats

as of 9/20/2026

Inspections

that found this code

Violations

total written

OOS rate

11.5%

7 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: Cargo Protection - HM
Regulation §: 177.840G-HMHC
Severity weight: 4
Used in SMS: Yes
Status: Active
Updated: 9/20/2026

Last updated September 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.

What 177.840G-HMHC means — and how to avoid it

In plain English

In plain terms, 177.840G-HMHC is cited for hM (Highway Carriage) - Liquid discharge valve not closed during the transportation of Class 2 hazardous materials.

What the inspector checks

•Enough tiedowns for cargo length/weight and working load limit
•Tiedowns, chains, straps, and binders not damaged or loose
•Blocking/bracing and edge protection where needed

How to prevent it

✓Learn the working-load-limit math for your loads and carry extra straps/chains
✓Re-check securement within the first 50 miles and at every stop
✓Replace frayed straps and bent binders before the trip

How it affects your CSA

up to 12 pts (fresh)

Severity 4/10. A fresh citation counts at the 3× time weight — up to 12 points toward the Hazardous Materials Compliance BASIC — then tapers to 2× after 6 months and 1× after a year, dropping off the score at 24 months.

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 177.840G-HMHC 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 177.840G-HMHC →Read the DataQs guide first

More codes in Hazardous Materials Compliance

Same BASIC category — ranked by national citation volume

View all Hazardous Materials Compliance codes →

Other Cargo Protection - HM codes

Codes under the same FMCSA violation group

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Frequently asked questions about 177.840G-HMHC

What does violation 177.840G-HMHC mean?

177.840G-HMHC is the FMCSA roadside-inspection violation code for "HM (Highway Carriage) - Liquid discharge valve not closed during the transportation of Class 2 hazardous materials.", part of the Cargo Protection - HM group, cited under 49 CFR §177.840G-HMHC.

What BASIC does 177.840G-HMHC affect?

177.840G-HMHC falls under the Hazardous Materials Compliance BASIC in the FMCSA Safety Measurement System (SMS).

What is the CSA severity weight of 177.840G-HMHC?

177.840G-HMHC carries a severity weight of 4 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 177.840G-HMHC an out-of-service (OOS) violation?

No. 177.840G-HMHC 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 177.840G-HMHC add to a carrier's score?

The point contribution of 177.840G-HMHC depends on its severity weight (4/10) 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.

How can a driver prevent 177.840G-HMHC?

Learn the working-load-limit math for your loads and carry extra straps/chains; Re-check securement within the first 50 miles and at every stop; Replace frayed straps and bent binders before the trip.

Can 177.840G-HMHC be challenged through DataQs?

Yes. If you believe 177.840G-HMHC 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 177.840G-HMHC Hazardous Materials Compliance BASIC Carrier CSA lookup CSA glossary

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