What 393.50(d) means in plain language
A 393.50(d) citation means a federal inspector found your steering mechanism to be defective, broken, or not functioning properly. This is one of the most critical systems on your truck—it's what lets you control direction, respond to road hazards, and keep your vehicle stable during lane changes and turns.
The regulation covers the entire steering assembly: the steering wheel, column, gearbox, linkage, tie rods, ball joints, and any other component that transmits your input to the wheels. If any part of that chain is cracked, loose, has excessive play, or doesn't respond as designed, you're in violation. Inspectors check for things like worn steering components, missing fasteners, bent tie rods, or a steering wheel that feels mushy or unresponsive.
This isn't a warning or a minor maintenance item. A failed steering system can cause you to lose control at highway speeds. That's why roadside inspectors take it seriously, and that's why you should too.
What our enforcement data actually shows
Across our 13 million+ roadside inspection records, we see 506 all-time citations for steering mechanism defects. Here's what stands out: only 0 citations appeared in the last 12 months, and 0 in the last 90 days. That's a sharp contrast to the overall enforcement volume you'd expect, which suggests either improved steering maintenance across the industry or a shift in inspection priorities.
When violations do occur, inspectors place trucks out of service only 1.0% of the time—just 5 out of 501 citations. Compare that to the all-FMCSR average out-of-service rate of 31.4%, and you'll see that 393.50(d) is handled more leniently on the roadside. Most drivers cited for this violation are allowed to continue, likely because the defect can be addressed quickly or isn't immediately catastrophic. However, that doesn't mean the violation is minor—it means inspectors sometimes believe the risk is manageable enough to let you drive to a repair facility.
By citation count, 393.50(d) ranks #918 out of 3,036 FMCSR codes, placing it well below the most-cited violations. But rarity doesn't equal unimportance; steering failures are safety-critical.
Who gets cited most
Our inspection data does not identify citations by state in the records for this code. However, we do see patterns across carriers. J B HUNT TRANSPORT INC (USDOT 80806) leads with 7 citations, followed by BEAVERS TRANSPORT LLC (USDOT 3536686) and PZ TRUCKING SERVICES LLC (USDOT 3904079), each with 3 citations. Other carriers such as MERCEDES WASTE & TRUCKING LLC, TRANSPORTES DOSG SA DE CV, INLAND ENVIRONMENTS LTD, USA TRUCK LLC, WASTE MANAGEMENT OF WISCONSIN INC, CRESCENCIO LUNA MARTINEZ, and TORNADO BUS COMPANY each account for 2 citations in our database.
These numbers don't point to systemic negligence; they reflect the reality that larger fleets and waste-hauling operations tend to accumulate more citations simply because they run more miles. Smaller carriers may see fewer roadside inspections overall.
How severe is this compared to similar codes
Steering defects fall into the Vehicle Maintenance category. Here's how 393.50(d) stacks up against related violations in our database:
393.9(a) — Inoperable required lamps has 660,737 citations with a 15.4% out-of-service rate. That's a far more common violation, but steering is arguably more safety-critical than lighting.
396.3(a)(1) — Inspection/repair/maintenance general logged 236,919 citations with a 45.3% out-of-service rate. That catch-all code produces more out-of-service orders, suggesting inspectors view maintenance violations under that statute as more warrant closure.
393.47E — Slack adjuster defective shows 180,363 citations with a 0.0% out-of-service rate. Like 393.50(d), brake-system defects are often cited but rarely lead to immediate shutdown, probably because a driver can limp to a shop and get it fixed.
The pattern is clear: steering violations exist in a middle zone—serious enough to cite, but not so obviously unsafe that inspectors universally pull trucks off the road.
How to avoid it
Steering defects are preventable with disciplined pre-trip inspection and timely maintenance. Here are concrete actions:
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Check steering play before every shift. Turn the steering wheel fully left and right while parked, then gently with the engine running. Feel for excessive dead-zone (movement before the wheels respond). If it takes more than 10–15 degrees of wheel rotation to see the front end move, something is loose.
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Look for visible wear on tie rods and ball joints. Get under the truck with a flashlight. Grab the tie rod or ball joint by hand (or use a pry bar carefully). Any movement that doesn't come from the wheel itself means wear. Cracking, bending, or missing dust boots are red flags.
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Listen for clunks and groans. Drive slowly over a bump or in a circle. Steering noise—clunks, creaks, or grinding—often precedes failure. Address it before an inspector does.
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Check fasteners on the steering column and linkage. Vibration works bolts loose over time. Look for missing cotter pins, bent bolts, or fasteners that can be turned by hand.
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Inspect your specific truck model closely. Our data shows Freightliner (FRHT) units account for 52 citations, Mack trucks 22, Peterbilt 22, and Kenworth 21. If you drive one of these makes, steering maintenance is especially critical—either because these models see more miles or because certain designs have wear patterns. Know your truck's steering geometry and service schedule.
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Don't ignore steering drift or pulling. If your truck wants to veer left or right on a straight road, a steering or suspension issue is the likely cause. This is both a safety hazard and a violation waiting to happen.
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Have a qualified mechanic inspect the entire steering system annually or whenever you notice any change in responsiveness. Preventive maintenance is far cheaper and safer than a roadside citation or a loss-of-control incident.
Remember: steering failures happen gradually. Tight inspection habits catch them before an inspector does.