What 393.45B2UV means in plain language
This regulation targets the physical condition of the brake tubing and hoses on your commercial motor vehicle. Specifically, inspectors are looking for hoses or tubing that show signs of wear, chafing, crimping, or any other form of physical damage that could compromise how your brakes function. If a line looks like it has been rubbing against a frame rail, pinched by a component, or beaten up by road debris, that is what triggers this citation.
The rule exists because damaged brake lines are a direct path to brake failure. A chafed hose that bleeds air pressure slowly or a crimped line that restricts flow can quietly degrade your stopping power before you even notice something is wrong. Inspectors are trained to look at hose routing, connection points, and the condition of the tubing surface during a Level I or Level II inspection.
It is worth noting that this violation is marked OOS-ineligible under the standard criteria — meaning a citation alone does not automatically put your truck out of service. However, as you will see in the data below, it still happens in a meaningful share of inspections, and the downstream consequences on your CSA score are real.
What our enforcement data actually shows
Across our database of 13 million+ inspections, 393.45B2UV has generated 55,783 all-time citations, making it the 55th most-cited code out of 3,036 total FMCSR codes. That is not a fringe violation — this is a high-volume citation that inspectors are actively writing every day.
In the last 12 months alone, our inspection records show 38,344 citations under this code. In just the last 90 days, 9,862 citations were recorded. The monthly trend data shows enforcement has been climbing: from 2,749 citations in December 2025 to 3,805 in January 2026, 4,018 in February 2026, and 4,391 in March 2026 — the highest single month in the trailing 12-month window.
On out-of-service outcomes: although 393.45B2UV is not OOS-eligible on paper, our records show that 3,617 out of 55,783 inspections still resulted in an OOS placement, producing a 6.5% OOS rate. Compare that to the all-FMCSR average OOS rate of 31.4% — this code sits well below that average, which reflects its ineligible classification. Still, a 6.5% chance of getting parked is not zero, and in the cases where inspectors find the hose damage severe enough to cite additional brake-related violations, OOS placement becomes much more likely.
The CSA severity weight for this code is 7, which means every citation lands on your PSP record and pushes your carrier's BASIC score in the Vehicle Maintenance category. That matters when shippers and brokers pull scores.
Who gets cited most
Looking at the last 180 days, three states dominate citation volume. Texas leads decisively with 18,902 citations — a reflection of the high volume of cross-border and interstate commercial traffic moving through that state. New Mexico is a distant second at 340 citations. Illinois follows at 9 citations in the same window.
The OOS rate variation across these states is significant and worth understanding. Texas came in at a 5.8% OOS rate. New Mexico's rate was substantially higher at 24.1%, even though its raw citation count is far lower — inspectors in New Mexico appear to be finding more severe conditions when they do write this code. North Carolina, while showing only 3 citations in this period, recorded the highest OOS rate of the listed states at 66.7%, though the small sample size means that figure should be interpreted carefully.
In terms of fleet-level exposure, our data shows carriers such as SERVICIO INTERNACIONAL DE ENLACE TERRESTRE SA DE CV (USDOT 818175) with 542 all-time citations under this code, and OPERADORA DE TRANSPORTE INTERNACIONAL SA DE CV (USDOT 683428) with 442 citations. The concentration of citations among carriers operating cross-border routes into Texas aligns with the state-level data.
How severe is this compared to similar codes
Within the Vehicle Maintenance category, 393.45B2UV sits at 55,783 citations — well below the highest-volume peers but still significant. Consider 393.9(a) — Inoperable Required Lamps — which has 660,737 all-time citations in our database, more than ten times the volume of this code, at a 15.4% OOS rate. That code is far more commonly written but carries a comparable or slightly higher OOS rate.
Look at 396.3(a)(1) — Inspection, Repair, and Maintenance (general) — which has 236,919 citations and a steep 45.3% OOS rate. When that code appears alongside 393.45B2UV in the same inspection, the risk of being placed out of service rises sharply, because the inspector is now documenting both a specific defect and a systemic maintenance failure.
Another relevant peer is 393.47E — Slack Adjuster Defective — with 180,363 citations and a 0.0% OOS rate in its standard form. Our co-occurrence data shows that code appears in 1,489 of the same inspections as 393.45B2UV in the last 90 days, which tells you that brake system deficiencies tend to cluster — a problem with tubing rarely shows up alone.
How to avoid it
The co-occurrence patterns in our data tell a clear story: 393.45B2UV almost never shows up in isolation. Here is what to look for before you leave the yard:
- Trace every brake line during your pre-trip. Follow each hose from the glad hands or ABS module along the frame to the chambers. Look for spots where tubing rubs against metal edges, axle components, or wiring harnesses. Chafing at contact points is the most common defect pattern.
- Check for crimping at bends and clamp points. Hoses that have been rerouted, repaired, or clamped improperly can develop internal restrictions that are invisible from the outside. If a hose has a sharper-than-factory bend, flag it for a shop inspection before your run.
- Pay extra attention on Freightliner and Kenworth equipment. Our records show FRHT units account for 18,287 all-time citations under this code, and KW units account for 9,818. If you operate either platform, the brake line routing on those chassis has historically produced higher inspection findings.
- Do not skip the slack adjuster check. With 1,489 shared inspections in the last 90 days, 393.47E co-occurs with this code frequently. If your automatic slack adjusters are not maintaining proper pushrod travel, the system is under stress that can accelerate hose wear.
- Address inoperable lamps before departure. Code 393.9 appeared in 2,368 shared inspections in the last 90 days. An inspector who stops you for a burned-out light will walk the truck — and walk past your brake hoses.
- Review your last maintenance records for fuel system work. Code 396.5B — Fuel system leak — appeared in 1,540 shared inspections. Shops that miss fuel leaks often miss brake line condition too, which points to a pre-trip verification problem, not just a repair problem.
The pre-trip inspection on brake lines takes under five minutes if you know the route of each hose on your specific unit. That five minutes is the difference between a clean inspection report and a severity-7 hit to your carrier's BASIC score.