What 393.50D means in plain language
A 393.50D citation means an inspector found your steering mechanism to be defective, broken, or not functioning properly. This covers the entire steering system—the wheel, column, gearbox, linkage, and any hydraulic or mechanical components that allow you to control the direction of your vehicle.
The regulation requires that your steering mechanism operate safely and responsively. If an inspector found play in the steering wheel, loose connections, binding, or any component that compromises your ability to steer smoothly and predictably, they will cite you under 393.50D. This isn't a minor issue: faulty steering directly endangers you, your cargo, and everyone sharing the road.
Unlike some maintenance violations, 393.50D citations are not automatically out-of-service. However, the defect itself may have been severe enough that the inspector determined your vehicle unsafe to operate, in which case you would be directed to repair it before proceeding.
What our enforcement data actually shows
Across our 13 million+ inspection records, 393.50D has been cited 338 times all-time, with 207 citations in the last 12 months and 50 in the last 90 days. This ranks 393.50D at #1049 out of 3,036 FMCSR codes by citation volume—a relatively uncommon citation, which reflects that most fleets catch steering issues before roadside inspection.
The critical distinction: our data shows a 0.0% out-of-service rate for this code. None of the 338 citations resulted in an out-of-service order. This is substantially lower than the all-FMCSR average out-of-service rate of 31.4%. What this tells you is that inspectors are citing the violation but not immediately impounding your vehicle. That said, receiving this citation is a clear signal that your steering system requires immediate attention. The lack of OOS placement does not mean the defect is minor—it means you have the opportunity to repair and continue operating, but you must act quickly.
Monthly data over the past 12 months shows citation activity ranging from 1 to 35 per month, with notable peaks in October 2025 (35 citations) and January 2026 (28 citations). The variability suggests seasonal or regional enforcement patterns rather than a steady trend.
Who gets cited most
Our inspection records show Texas leads all states with 110 citations over the last 180 days, followed distantly by New Mexico with 2 citations and Illinois with 1. Texas represents the overwhelming majority of 393.50D enforcement activity in our database. The out-of-service rate is 0.0% across all three states, indicating consistent enforcement practice.
At the carrier level, our data shows fleets such as Crescencio Luna Martinez (USDOT 799584) with 4 citations, and Mora Services Corporation (USDOT 4319794) with 3 citations across our all-time record. This does not imply systematic negligence; rather, it reflects that these carriers operate in high-inspection regions or maintain larger fleets with greater exposure to roadside checks.
How severe is this compared to similar codes
Within the Vehicle Maintenance category, steering defects sit in a unique position. Compare 393.50D to three common peer codes:
393.9 (Inoperable Required Lamp): 660,737 citations all-time with a 15.4% out-of-service rate. Lighting violations are far more frequent but have a higher OOS rate, suggesting they are treated more seriously when found in combination with other defects.
393.47E (Slack Adjuster Defective): 180,363 citations with a 0.0% out-of-service rate, identical to 393.50D. Both are critical brake and steering components that inspectors cite but don't automatically pull from service, likely because drivers often address them immediately or they are discovered in isolation.
396.3(a)(1) (General Inspection/Repair/Maintenance): 236,919 citations with a 45.3% out-of-service rate. This catch-all violation is placed out of service nearly half the time because it often reflects broader maintenance failure, whereas 393.50D is specific and correctable.
How to avoid it
Our enforcement data reveals patterns in what else inspectors find during 393.50D citations. The most common co-occurring violations tell us what to monitor:
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Perform a comprehensive pre-trip steering inspection every day. Check for play in the steering wheel by turning it fully left and right while parked. Feel for any binding, grinding, or unusual resistance. Our data shows 393.9 (inoperable lamps) frequently appears alongside steering citations, suggesting inspectors are conducting thorough walkarounds when they encounter steering issues—so fix multiple systems, not just one.
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Inspect steering linkage, tie-rods, and ball joints for wear. 393.53B (steering system components worn) co-occurs in 12 of the last 90 days' inspections, indicating that general wear precedes steering defects. Tighten any loose connections and replace components showing visible movement or corrosion.
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Check brake systems in tandem with steering. 393.47E (slack adjuster defective) and 393.45B2UV (brake tubing inadequate) appear frequently alongside steering citations. Worn brakes and poor steering control often develop together because both affect vehicle stability and control.
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Monitor vehicle condition by make. Our data shows Freightliner (FRHT) leads with 97 citations, followed by Mack (58) and Peterbilt (34). If you operate one of these makes, be particularly vigilant about steering play and linkage maintenance, as these vehicles appear more frequently in our steering-defect records.
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Verify your vehicle passed its most recent periodic inspection. 396.17C (no proof of periodic inspection) co-occurs in 11 inspections. Roadside inspectors check for evidence that your vehicle has been formally inspected and documented. Maintain your inspection records and ensure steering is signed off by a qualified mechanic.
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Do not operate if steering feels loose or unresponsive. The regulation requires the steering mechanism to function properly. If you notice excessive play, delayed response, or any grinding or binding, stop and document the issue before continuing. This protects you from citation and, more importantly, from losing control.