Answers for drivers cited under 178.337-9 (MC331 pressure relief devices). What happens next, OOS risk, and how this compares to similar hazmat violations.
Ranks #2,811 of 3,146 FMCSR codes by citation frequency • OOS rate of 0.0% is below the FMCSR-wide average of 33.3%.
MC331 Pressure relief devices
Direct answers grounded in TruckCodex inspection data
No. Across our 13 million inspection records, the 0.0% out-of-service rate for 178.337-9 means this violation does not result in immediate vehicle removal. That's significantly lower than the 31.4% average OOS rate across all FMCSR codes. You'll be cited, but your truck stays on the road while you address the pressure relief device defect.
Much less severe than comparable hazmat citations. Our records show peer codes in the same Hazardous Materials category carry far higher OOS rates—for example, general loading/unloading hazmat violations (177.834A-HMC) hit 99.2% OOS rate with 3,954 citations, and placard violations (177.817(a)) reach 97.9% OOS. At 0.0% OOS, 178.337-9 is among the lowest-risk hazmat findings in our database.
No, it's rare. Our inspection database shows only 1 all-time citation for this code, making it rank #2796 out of 3,036 FMCSR codes by enforcement volume. In the last 12 months and last 90 days, we recorded zero citations. This violation is infrequent enough that most drivers and fleets never encounter it.
First, obtain and document the full citation details from the inspector. Second, inspect your MC331 pressure relief devices to identify the specific defect noted. Third, contact a qualified technician certified to work on hazmat equipment—pressure relief systems require expert assessment. Finally, retain documentation of the repair or compliance action taken. Given the rarity of this citation, your state's hazmat enforcement unit may help clarify exact requirements for your equipment type.
Yes, you can file a DataQs (Request for Data Query) challenge to dispute factual errors in the citation record. The process applies to all FMCSR violations, including 178.337-9. However, DataQs is limited to correcting administrative errors—wrong dates, carrier names, or inspection details. If the inspector correctly documented a pressure relief device defect, the citation will stand. Consult the FMCSA DataQs portal or your safety manager for state-specific filing deadlines and procedures.
Thompson Gas LLC (USDOT 2812287) received the sole citation for this code in our 13 million-record database. With only 1 all-time enforcement event, this violation is so rare that most carriers have zero citations. If your company was cited, you're in extremely small company—both numerically and in terms of the hazmat industry.
While the citation carries no immediate out-of-service consequence, pressure relief devices on MC331 tanks are critical safety components for hazardous materials transport. Repair urgency depends on your commodity and state regulations, but do not delay. Our data shows zero citations in the last 90 days, suggesting inspectors are not actively targeting this code—yet neglecting it could result in operational shutdown if a subsequent inspection finds the defect unresolved.
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.
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