What 393.93B-TS means in plain language
FMCSR 393.93B-TS addresses temporary seating installed for the driver in a commercial motor vehicle. This code applies when a truck has been fitted with a seat that is not permanently installed or is makeshift in nature—essentially, any seating arrangement that doesn't meet the durability and safety standard of factory-installed driver seating.
The regulation exists because your seat isn't just a comfort feature. It affects how you're positioned relative to the steering wheel, pedals, and controls, and influences how effectively a seat belt can restrain you during sudden maneuvers or crashes. A temporary or unstable seat undermines that protection and can contribute to loss of vehicle control.
If an inspector finds that your driver's seat is temporary, non-secured, or otherwise not permanently affixed to the vehicle frame, you'll be cited. This is a maintenance and equipment violation—not a roadside safety infraction.
What our enforcement data actually shows
Across our 13 million+ inspection records, 393.93B-TS remains a relatively uncommon citation. We've recorded 11 all-time citations for this code, with 9 citations in the last 12 months and 2 in the last 90 days. This ranks 393.93B-TS at #2167 out of 3,036 FMCSR codes by citation volume—meaning it's cited far less frequently than major violations.
However, when cited, the consequences are significant. Our data shows an 81.8% out-of-service (OOS) rate for this code—meaning roughly 9 out of 11 vehicles cited were placed out of service. This is substantially higher than the all-FMCSR average OOS rate of 31.4%, indicating that inspectors treat temporary seating as a serious defect that typically renders a vehicle unsafe to operate until corrected.
In the last 90 days, we've seen 2 citations. One was placed out of service; the other was not. Over the last 12 months, the citation trend has remained steady with occasional spikes, including 2 citations in September 2025 (both OOS) and 2 in November 2025 (1 OOS).
Who gets cited most
Our inspection records show citations for 393.93B-TS are geographically sparse. In the last 180 days, we recorded 1 citation each in California, New Jersey, Nevada, and nationwide (likely a handful of states not individually listed). Nevada recorded 1 citation with a 100.0% OOS rate, while California and New Jersey each had 1 citation with a 0.0% OOS rate—suggesting variation in enforcement severity or in the severity of the defect cited.
By carrier, our data shows TS TRUCKING (USDOT 4433204) with 2 all-time citations—the highest count in our database for this code. Other carriers with single citations include Luis Eusebio Salgado Esquer, Isidoro Mata Lopez, One Southeast Missouri Transport LLC, Vektor Corporation Inc, John Lambirth Trucking Inc, CNA Materials LLC, Bear Cooking Oil USA Corp, Green Team of NY Services Corp, and IBLT Trucking Inc. This wide distribution across small carriers and owner-operators suggests the violation is not concentrated in a particular fleet operation or carrier type.
How severe is this compared to similar codes
Compare 393.93B-TS to other vehicle maintenance codes in the same category. Inoperable required lamps (393.9(a)) has been cited 660,737 times with a 15.4% OOS rate—far more common but much less likely to be placed out of service. Inspection/repair/maintenance general (396.3(a)(1)) has 236,919 citations with a 45.3% OOS rate. No proof of periodic inspection (396.17C-PI) shows 212,081 citations but a 0.0% OOS rate.
The 81.8% OOS rate for 393.93B-TS sits well above nearly all peer codes in this category. Only a handful of codes—those involving brake defects or suspension failure—match this severity. This tells you that when an inspector cites temporary seating, they are almost always confident the defect is critical enough to stop the vehicle.
How to avoid it
Prevent a 393.93B-TS citation by ensuring your driver's seat meets regulatory standards before you roll:
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Inspect your seat mounting before every pre-trip. Check that the seat is bolted securely to the vehicle frame and does not move, rock, or slide when you apply firm downward and lateral pressure. A seat mounted only with fasteners that pass through the seat pan into the frame—not strapped or welded—is vulnerable.
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Replace any seat that shows signs of wear or damage to its base. If the seat cushion is cracked, the bottom pan is bent, or welds are visible (indicating a repair), have it professionally replaced or certified sound before your next inspection.
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Do not use folding camp chairs, non-integrated jump seats, or aftermarket add-on cushions as primary driver seating. Temporary or portable seating is exactly what this code targets.
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Check seat belt attachment and routing. Our co-occurring violation data shows seat belt failures (392.16AD and 392.16B-DPASS) often appear in the same inspections as temporary seating citations. A loose or unstable seat makes proper belt restraint impossible, so an inspector may cite both.
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If your vehicle is a commercial model (HINO, Freightliner, Mack, International, or similar), verify the OEM seat is installed. Aftermarket or modified seats are more likely to be flagged. Our data shows HINO vehicles appeared twice in citation records for this code, suggesting some models or modifications may attract closer scrutiny.
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During any vehicle repair or refurbishment, ensure the seat is re-bolted and tested for stability. If your suspension was recently serviced (393.207A-STBW) or brakes worked on (393.45D-B), the seat may have been removed and incorrectly reinstalled.
If you receive a citation for 393.93B-TS, the most likely outcome based on our data is immediate out-of-service status. Your vehicle will not be legal to operate until the seat is corrected and re-inspected. Address it at a qualified truck repair facility immediately, document the repair, and request a new safety inspection before you resume operation.