What 393.50B means in plain language
A 393.50B citation means a roadside inspector found that your steering mechanism was defective, broken, or not functioning properly. This covers the entire steering system—the wheel, column, gearbox, linkages, and any hydraulic or mechanical component that translates your hand inputs at the wheel into actual directional control of the truck.
The regulation doesn't require perfection, but it does require the steering to work as designed. Common reasons for citations include excessive play in the steering wheel (more slack than manufacturers allow), broken tie rods or drag links, leaking or inoperable power steering systems, or any damage that makes the truck harder to steer or unsafe to control. If an inspector turns the wheel and feels excessive free movement before the front tires respond, or finds visible damage to steering components, you get flagged.
This is a safety issue: a defective steering mechanism can make your truck unpredictable or uncontrollable, especially at highway speeds, in bad weather, or during emergency maneuvers. Inspectors take it seriously because steering failure puts you and everyone else on the road at risk.
What our enforcement data actually shows
Across our 13 million+ inspection records, 393.50B is cited relatively rarely—53 all-time citations place it at rank #1609 of 3,036 FMCSR codes by enforcement volume. In the last 12 months, we recorded 31 citations, and in the last 90 days, 8 citations. The citation rate has been steady; March 2026 saw 5 citations, and monthly counts over the past year have ranged between 1 and 5.
Critically, none of the 53 all-time citations resulted in an out-of-service order. The OOS rate for 393.50B is 0.0%. This is substantially better than the all-FMCSR average OOS rate of 31.4%, suggesting that when inspectors cite this code, they typically view it as a defect that does not immediately prevent the truck from being driven to a repair facility, or they are citing it after you've already fixed or disclosed the issue. That said, do not interpret a low OOS rate as a sign that this violation is minor—steering is critical, and while you may not be ordered off the road on the spot, you remain liable for the citation and any safety consequences.
Who gets cited most
Our inspection records show that Texas accounts for the majority of 393.50B citations in the last 180 days, with 17 citations and a 0.0% OOS rate. The data is heavily concentrated in Texas; we have no other states with material citation counts in the recent period, which reflects both the state's large trucking population and the particular focus of roadside enforcement in that region.
At the carrier level, our data shows fleets such as TOP FLIGHT TRUCKING & LOGISTICS LLC (USDOT 2285028) with 2 citations all-time, and RAUL CASTRO (USDOT 3191825) also with 2 citations. Several other carriers—BASDEN INDUSTRIES INC, ODILON GONZALEZ, SMYRNA READY MIX CONCRETE LLC, and others—each have 1 citation. These numbers are small in absolute terms and do not suggest systemic steering problems at any particular carrier; they simply reflect which operators have been stopped and inspected in the jurisdictions where 393.50B is enforced.
How severe is this compared to similar codes
393.50B sits in the Vehicle Maintenance category alongside several higher-volume codes. For context:
- 393.9 (Inoperable Required Lamp) has been cited 180,097 times with a 6.9% OOS rate. Lamps are important but less safety-critical than steering, and the OOS rate is higher, meaning inspectors more often remove trucks for light defects.
- 393.78 (Windshield condition defective) shows 157,894 citations with a 0.3% OOS rate—similar to 393.50B in that trucks are rarely ordered off-road for windshield issues, but windshield defects are cited far more frequently.
- 396.3(a)(1) (Inspection/repair/maintenance - general) is the highest-volume code in the category at 236,919 citations and carries a 45.3% OOS rate, reflecting that general maintenance failures are broad and often serious enough to ground a truck.
The 393.50B CSA severity weight is 8, which is moderate. You won't see this code on every inspection, and when it does appear, the outcome is seldom an immediate out-of-service order. However, the rarity of this citation and the focus on steering safety means inspectors are not citing it frivolously—if they flag your steering, it is a real defect that must be corrected before you return to the road.
How to avoid it
Use these concrete, pre-trip actions to catch steering issues before an inspector does:
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Check steering wheel play every morning. With the truck stopped and parked on level ground, sit in the driver's seat with the engine off, grab the wheel at 3 o'clock and 9 o'clock, and gently wiggle it. Any free movement of more than an inch or two before the front tires move is too much. If you feel excessive play, do not drive the truck; document it and report it to maintenance.
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Listen and feel while driving. Take your truck on a straight, empty road at low speed. The steering should respond smoothly and predictably. If the wheel feels loose, unresponsive, or if the truck drifts when you're holding it straight, stop immediately and have it inspected. Do not wait for a roadside stop.
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Inspect tie rods, drag links, and steering linkage visually. Get under the front end (with the truck safely supported) and look for bent, cracked, or severely corroded steering components. Move them gently by hand to check for excessive movement in any joint. Hydraulic lines should not be leaking or kinked.
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Check power steering fluid level and condition. If your truck has power steering, the fluid should be at the correct level (check your manual), clear or slightly amber, and free of metal shavings or cloudiness. Low or dirty fluid can make steering feel weak or sluggish and will eventually damage the pump and other components.
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Monitor for related defects. Our inspection records show that 393.50B often co-occurs with 393.78 (windshield condition defective) and 393.9 (inoperable required lamp) in the same inspection. This suggests that trucks flagged for steering defects may also have other maintenance gaps. Keep your pre-trip inspection thorough and systematic—do not stop after checking the steering.
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Know your truck's make and maintenance history. Our data shows that FRHT (Freightliner) trucks account for 14 of the 53 citations, followed by KW (Kenworth) with 10 and MACK with 9. If you drive one of these makes, be especially attentive to steering wear patterns, as parts may fatigue predictably. Consult your manufacturer's service bulletins and your fleet's maintenance schedule.
The bottom line: steering is not something you can defer. If you suspect a problem, fix it before you're inspected. A steering citation may not land you out-of-service, but it will damage your safety record, cost you time and money, and leave you liable if an accident follows.