What 393.51D-B means in plain language
Steering wheel free play is the amount of slack or movement you can feel in your steering wheel before the front wheels actually respond. Every steering system has some tolerance built in—that's normal and expected. The regulation sets a maximum limit for how much free play is acceptable based on the type of steering system your truck uses.
When an inspector measures your steering wheel and finds it exceeds that allowable limit, you've been cited for 393.51D-B. This typically means wear in the steering column, gearbox, or tie-rod connections has created too much play. It's a safety issue because excessive free play reduces your control precision, especially at highway speeds or in emergency maneuvers.
The citation itself does not result in an out-of-service order. You can continue driving, but you need to address the underlying steering component wear before your next inspection.
What our enforcement data actually shows
Across our 13 million+ inspection records, 393.51D-B is rarely cited. All-time, we have recorded only 8 citations for excessive steering wheel free play. In the last 12 months, inspectors issued just 1 citation for this code, and over the last 90 days, there have been 0 citations.
None of the 8 all-time citations resulted in an out-of-service placement, giving this code a 0.0% OOS rate. This stands in sharp contrast to the all-FMCSR average OOS rate of 31.4%, reflecting that inspectors treat steering wheel free play violations as maintenance defects rather than immediate safety failures that warrant removal from service.
Nationally, 393.51D-B ranks #2269 out of 3,036 FMCSR codes by citation volume. The rarity of enforcement means this violation is either caught infrequently during roadside inspections, or steering systems are generally well-maintained across the industry.
Who gets cited most
Over the last 180 days, our inspection records show Georgia recorded 1 citation for 393.51D-B, with a 0.0% out-of-service rate. With such limited citation volume in the enforcement database, state-level comparison is not meaningful.
All-time, our records identify carriers including Ideker Inc, Rolando Villanueva Navarro, Flatland Trucking Inc, Transportation and Cargo Solutions S de RL de CV, Frisco Coachline LLC, Quality Tank SA de CV, Soporte y Servicios en Productos Industriales S de RL de CV, and Smallville Logistics LLC, each with 1 citation in our database. The small citation count means no carrier exhibits a pattern of steering wheel free play violations.
How severe is this compared to similar codes
Comparing 393.51D-B to other vehicle maintenance codes shows significant differences in citation frequency and enforcement outcomes. The code 393.9(a) for inoperable required lamps has generated 660,737 citations all-time with a 15.4% OOS rate—orders of magnitude higher enforcement volume. Similarly, 396.3(a)(1) for general inspection and maintenance has 236,919 citations and a 45.3% OOS rate.
On the lower end of enforcement, 393.47E for defective slack adjusters shows 180,363 citations but a 0.0% OOS rate, matching 393.51D-B's placement pattern. And 393.78 for windshield defects has 157,894 citations with only a 0.3% OOS rate. The data indicates that steering wheel free play, like several brake and lighting maintenance issues, is documented by inspectors but rarely triggers removal from service.
How to avoid it
Steering system inspection requires deliberate attention during your pre-trip walk-around. Here are concrete actions to keep your steering wheel free play within limits and avoid citations:
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Perform the steering wheel test before every trip. Sit in the cab with the engine off and wheels straight. Rotate the steering wheel hand-over-hand and count the degrees of rotation before the front wheels move. If it feels loose or the wheel spins more than what your training taught you, flag it for service immediately.
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Check steering column connections under the dash. Look for worn U-joints, loose fasteners, or play in the column shaft itself. Tighten any loose bolts and note wear patterns for your maintenance team.
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Inspect tie-rod ends and drag-link connections. Walk around to the front axle and visually check where the steering linkage connects to the wheel hubs. Grasp the tie-rod and try to move it by hand—any lateral movement or clicking indicates wear that will increase free play.
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Listen and feel during a slow-speed test drive. Before heading to the highway, drive at 5–10 mph in an empty lot and feel how the steering responds. Any delay between wheel input and vehicle response suggests developing free play.
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Document maintenance history. Keep records of steering component inspections and replacements. If you've had recent work on the steering column, gearbox, or linkage, carry proof that components were tested and adjusted to specification.
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Schedule preventive service based on mileage and age. Steering systems wear gradually. If your truck has high mileage or is aging, have your steering system inspected by a certified mechanic every 50,000 miles or annually, whichever comes first.