What 385.337B-OOSO means in plain language
FMCSR 385.337B-OOSO addresses compliance with specific vehicle and operational requirements under federal motor carrier safety regulations. When an inspector cites you for this code, they've determined your vehicle or your operation failed to meet the standard outlined in 49 CFR Part 385, Section 337(b).
This is a general administrative violation, not a brake, lighting, or structural defect. It typically involves documentation, certification, or operational procedures that should be in place before you depart. The violation itself does not automatically qualify your vehicle for immediate out-of-service removal on its face, but our inspection records show that in practice, it almost always results in one.
What our enforcement data actually shows
Across our 13 million+ roadside inspection records, 385.337B-OOSO ranks #599 out of 3,036 FMCSR codes by total citation volume. Over the past 12 months, we've recorded 1,020 citations for this code nationwide. In the last 90 days alone, 194 citations were issued.
The out-of-service rate for 385.337B-OOSO is exceptionally high: 95.7% of the 1,523 all-time citations resulted in an out-of-service order, meaning 1,457 drivers were pulled from service. This rate far exceeds the all-FMCSR average OOS rate of 31.4%—you are more than three times as likely to be sidelined by this code than by a typical FMCSR violation.
The trend over the past 12 months shows citations peaked in October 2025 with 136 citations issued, followed by December 2025 with 115 citations. The code has remained consistently active, with monthly citation counts ranging from 33 to 136.
Who gets cited most
Pennsylvania leads with 43 citations in the last 180 days (95.3% OOS rate), followed closely by New Jersey with 43 citations (93.0% OOS rate). New York reported 27 citations with a 100% OOS rate. Massachusetts had 28 citations but a notably lower OOS rate of 64.3%—the only significant variation among high-citation states.
Our data shows fleets such as HORIZEN LLC with 27 all-time citations and SAKARA LLC with 23 citations have experienced repeated enforcement for this code. LEASE AE LLC follows with 14 citations. These numbers reflect the cumulative citation history across their operations and do not necessarily indicate a pattern of intentional non-compliance, but they highlight that certain carriers encounter this violation more frequently than others.
How severe is this compared to similar codes
385.337B-OOSO belongs to the General/Admin FMCSR category. Peer codes in this category show dramatically different enforcement patterns. For example, 390.21TB2-DOT has 74,663 all-time citations but carries a 0.0% OOS rate, meaning nearly all violations are cited but drivers almost never sidelined. Similarly, 390.21T(b) has 61,097 citations with 0.0% OOS rate, and 390.21TB1-MC has 59,189 citations with 0.0% OOS rate.
The 95.7% OOS rate for 385.337B-OOSO is extraordinary within its category. Even 390.19B2-BIENNIAL, another general code, shows only 0.2% OOS rate across 16,142 citations. This tells you that 385.337B-OOSO violations are treated with far greater enforcement severity than most administrative citations.
How to avoid it
Our inspection records reveal which violations commonly appear alongside 385.337B-OOSO in the same roadside stop. Use this pattern to prevent the citation:
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Verify your proof of periodic inspection is current and in your cab. Code 396.17C-PI co-occurred in 47 of the last 90 days' 385.337B-OOSO inspections. Before each trip, confirm that your vehicle's periodic inspection documentation is valid, dated, and accessible to inspectors.
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Ensure your medical certificate is valid and on file. Code 391.41APC co-occurred in 34 recent inspections. Check your state licensing agency records to confirm your medical certificate is current. Carry proof if your state allows it in the vehicle.
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Review your hours-of-service records daily. Code 395.8A1-HOSP co-occurred in 31 recent inspections. Whether you use an electronic logging device or paper logs, have your record of duty status ready and compliant with the prescribed method before starting your shift.
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Check your vehicle's DOT number visibility and all safety markings. Codes 390.21TB1-MC and 390.21TB2-DOT co-occurred in 34 and 32 inspections respectively. Inspect your cab doors, bumper, or placards to confirm the USDOT number is clearly visible, legible, and properly displayed.
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Do not operate while fatigued. Codes 392.2-SLLUCR, 392.2-SLLSR, and 392.2-SLLIRP co-occurred frequently in recent inspections (37, 35, and 20 respectively). Operating while ill or fatigued is not just unsafe—it commonly appears in the same inspection as 385.337B-OOSO violations. Rest before your shift if you feel unfit.
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Perform a documented pre-trip inspection. The top vehicles cited for 385.337B-OOSO include Ford (232 citations), Freightliner (148), and other common makes. Before departing, walk around your vehicle, check lights, brakes, tires, and cargo securing. Document any defects and do not operate with safety deficiencies.
The high out-of-service rate for this code means that the inspector's primary concern at the roadside will be immediate compliance verification. Have all required documentation organized and accessible. If you do receive a 385.337B-OOSO citation, work with your carrier's safety department immediately—this violation does not go away with a warning and will almost certainly result in downtime.