What 393.45B2-B means in plain language
This citation covers brake tubing and hoses that are in a degraded or damaged condition — think hoses that have worn through their outer jacket, lines that have been pinched or kinked, fittings that show chafing from contact with frame components, or any tubing that has been physically compromised in a way that could affect brake system integrity.
The regulation applies to the entire brake plumbing system on your commercial motor vehicle. Inspectors aren't just looking at visible air lines running along the frame rails — they're checking anywhere brake tubing or flexible hose routes through the chassis, including areas near heat sources, moving suspension components, and anywhere a hose might rub against metal over time.
The practical takeaway is straightforward: if a hose looks worn, abraded, kinked, or damaged in any way that makes it look different from how it came from the factory, that's a citable condition. Inspectors are trained to flag it even if the brake system is still functional at the moment of inspection.
What our enforcement data actually shows
Across our database of 13 million+ inspections, 393.45B2-B has accumulated 12,302 all-time citations, placing it at #197 out of 3,036 FMCSR codes by citation volume — meaning this is a genuinely common finding, not an obscure technicality. The volume alone tells you inspectors encounter this regularly enough that it shows up in the top 7% of all federal codes by frequency.
The out-of-service picture is more reassuring than many brake-related codes. Our inspection records show that 430 of those 12,302 citations — a 3.5% OOS rate — resulted in the vehicle being placed out of service. The remaining 11,872 citations did not trigger an OOS order. For context, the all-FMCSR average OOS rate across all codes in our database is 31.4%, so 393.45B2-B comes in dramatically below that average. This is also consistent with the code being marked OOS-ineligible under standard criteria, though that 3.5% figure shows inspectors have discretion when conditions are severe enough.
One important note on recent trends: our data shows 0 citations in the last 90 days and 0 citations in the last 12 months. This likely reflects a data reporting lag or enforcement categorization shift rather than a sudden disappearance of the violation, so fleet managers should not interpret this as a signal to deprioritize brake hose inspections.
Who gets cited most
The statistics block for 393.45B2-B does not include a state-by-state breakdown, so we cannot identify the top citing states with specificity. What the carrier data does tell you is where citation volume has concentrated over time.
Our data shows fleets such as SERVICIO INTERNACIONAL DE ENLACE TERRESTRE SA DE CV (USDOT 818175) with 57 citations and TRANSPORTATION AND CARGO SOLUTIONS S DE RL DE CV (USDOT 779973) with 48 citations lead all carriers in all-time 393.45B2-B citation counts. The heavy representation of cross-border carriers in the top ten — with multiple Mexican-registered operations appearing — suggests that vehicles operating in high-mileage, cross-border corridors accumulate this violation at elevated rates, possibly due to road conditions, maintenance access patterns, or the increased inspection scrutiny that border crossings generate.
For domestic carriers, SWIFT TRANSPORTATION CO OF ARIZONA LLC (USDOT 54283) appears in the top group with 40 citations, and J B HUNT TRANSPORT INC (USDOT 80806) with 32 citations — both large-fleet operators where even a modest per-unit rate can generate significant absolute counts across tens of thousands of power units.
How severe is this compared to similar codes
Putting 393.45B2-B in context against peer codes in the Vehicle Maintenance category makes the enforcement landscape clearer.
The highest-volume code in the same category is 393.9(a) — Inoperable required lamps — with 660,737 all-time citations, more than 53 times the volume of 393.45B2-B. Its OOS rate sits at 15.4%, still well above the 3.5% seen here. That comparison tells you brake tubing issues are far less frequently cited than lighting defects, but they carry a lower OOS conversion rate.
More directly relevant is 396.3(a)(1) — Inspection, repair, and maintenance general — with 236,919 citations and a 45.3% OOS rate. That rate is nearly 13 times higher than 393.45B2-B's 3.5%, which illustrates that general maintenance failures tend to produce much more severe enforcement outcomes than a specific hose condition finding.
Also worth noting: 393.47E — Slack adjuster defective — has accumulated 180,363 citations within the same category. Slack adjuster defects carry a 0.0% OOS rate in our records, similar in that respect to the low OOS conversion seen here, but the citation volume is nearly 15 times higher, indicating that brake adjustment issues are far more routinely caught than brake tubing condition.
The bottom line from the peer comparison: 393.45B2-B is a mid-severity, moderate-volume code. It won't typically put you on the side of the road, but it carries a CSA severity weight of 7, which means it will add meaningful points to your safety measurement score.
How to avoid it
The vehicle make data in our records offers a useful clue. FRHT and FREIGHTLIN units account for 1,495 and 1,182 citations respectively — far more than any other make. Kenworth (451), INTL (420), and Peterbilt (401) follow. These are the most common trucks on the road, so raw volume is partly explained by fleet size, but it also tells you no platform is immune.
Here are concrete pre-trip actions that will catch 393.45B2-B conditions before an inspector does:
- Walk the entire brake line routing, not just visible sections. Crouch down and trace brake tubing from the glad hands through the frame to each axle. Look for any spot where hose contacts metal — those contact points are where chafing starts.
- Check hose condition near suspension pivot points. Flexible brake hoses near steer axles and drive axle suspension components flex with every wheel movement. Inspect for cracking, swelling, or kinking at the hose ends and at any clamp or bracket.
- Look for heat-related damage near exhaust routing. Brake lines that run near exhaust components can develop heat discoloration, brittleness, or outer jacket deterioration. If a hose feels stiff or shows any surface cracking, flag it before departure.
- Inspect all crimps and fittings for integrity. A hose that is structurally sound along its length but has a compromised fitting or a kinked section near a hard-line connection is still citable. Check that no fitting shows signs of mechanical damage or improper repair.
- After any suspension or brake work, re-inspect hose routing. Shop work that disturbs brake components is one of the most common ways hoses end up misrouted or in contact with surfaces they shouldn't touch. Verify routing is correct before pulling back onto the road.