What 393.55C2-B means in plain language
This violation covers situations where the coupling devices or towing methods on your commercial motor vehicle are found to be defective or inadequate. In practical terms, that means an inspector has determined that the hardware connecting your tractor to your trailer — or any towed unit to the vehicle pulling it — is not in acceptable working condition.
The regulation exists because a failed coupling in motion is a catastrophic event. An inspector citing 393.55C2-B is saying that what they observed creates an unacceptable risk of separation. The defect could involve a fifth wheel that isn't properly locked, a kingpin that has excessive play, safety chains or cables that are missing or improperly secured, or any other component that is part of how one unit is physically attached to another.
It is worth noting that 393.55C2-B is one of several coupling-related codes. Our data shows that 393.55C1-B appeared in 101 of the same inspections as this violation in just the last 90 days, and 393.55E-B appeared in 188 of the same inspections, which tells you inspectors often find multiple coupling issues at the same stop.
What our enforcement data actually shows
Across our 13 million inspection records, 393.55C2-B has accumulated 8,920 all-time citations. That places it at #242 out of 3,036 FMCSR codes by citation volume — solidly in the upper tier of enforcement activity. In the last 12 months alone, our inspection records show 6,214 citations for this code, and in just the last 90 days there were 1,218 citations. That is not a rarely enforced technicality; inspectors are writing this up regularly and the pace has been consistent.
Here is the number that should give you some immediate relief: the all-time out-of-service rate for 393.55C2-B is 0.0%. Out of 8,920 citations, exactly 1 vehicle was placed out of service. The national average OOS rate across all FMCSR codes is 31.4%, which means this code runs essentially at zero compared to that baseline. You were cited, but you almost certainly kept rolling.
That said, do not let the near-zero OOS rate make you complacent about the CSA severity weight. This code carries a severity weight of 8 — which is on the higher end of the scale. Every citation lands on your PSP record and feeds into your carrier's Vehicle Maintenance BASIC score. The citation does not stop your truck, but it does cost points.
Looking at the monthly trend, citations ran between 468 and 620 per month from May 2025 through March 2026, showing no sign of enforcement slowing down.
Who gets cited most
Looking at the last 180 days, Arizona leads all states with 617 citations, followed by Alabama with 233 and New York with 225. Ohio also sees heavy enforcement with 198 citations. None of these states show any meaningful OOS-rate variation — every state in our top-10 list is at 0.0% OOS — so where you operate changes your exposure to citations but not your odds of being parked.
Arizona's 617-citation total is more than double the next-closest state, which is consistent with the concentration of inspection activity along the I-10 corridor and the ports of entry that see heavy cross-border traffic.
Our data shows fleets such as NEW PRIME INC (USDOT 3706) with 35 citations and LIPSA TRANSPORTES SA DE CV (USDOT 2584144) with 33 citations at the top of the all-time carrier list. High citation counts at large-fleet carriers are a function of volume — more trucks on the road means more inspections — but the numbers do illustrate that no carrier size is immune to this violation.
How severe is this compared to similar codes
Within the Vehicle Maintenance category, 393.55C2-B is a mid-volume code. For comparison, 393.9(a) — Inoperable required lamps — has 660,737 citations in our database and carries a 15.4% OOS rate. That is roughly 74 times the citation volume of 393.55C2-B, and drivers cited for it face a real chance of being parked.
396.3(a)(1), the general inspection, repair, and maintenance code, has 236,919 citations and a 45.3% OOS rate — meaning nearly half the citations under that code result in a vehicle being taken out of service. By contrast, 393.55C2-B's 0.0% OOS rate makes it one of the least likely codes in its category to stop your truck.
A closer peer is 396.17C-PI — No proof of periodic inspection — which has 212,081 citations and a 0.0% OOS rate, similar to this code. Both codes generate significant CSA point exposure without typically resulting in an OOS order, which means their harm accumulates quietly on your record rather than showing up as a hard stop at the scale.
How to avoid it
The co-occurring violation pattern in our data gives a clear picture of what inspectors are finding alongside 393.55C2-B. Use these as your pre-trip checklist priorities:
- Inspect the fifth wheel locking mechanism before every dispatch. The kingpin should be fully seated and the locking jaws confirmed closed. Walk around and physically tug the trailer — do not rely only on a visual check.
- Check all safety chains, cables, and secondary attachment points. These are part of your coupling system and are exactly what this regulation covers. Make sure chains are properly crossed, have adequate tension, and are not dragging.
- Examine brake tubing and hoses at the trailer connection points. Our data shows 393.45D-B — brake tubing/hoses inadequate — appeared in 94 of the same inspections as 393.55C2-B in the last 90 days. A trailer that is poorly coupled often has related connection issues at the glad hands and ABS connectors.
- Verify all required lamps are operational. 393.9A-LIL appeared in 110 shared inspections and 393.9A-LSML in 86. An inspector who stops you for a light out is going to walk the entire truck-trailer connection.
- Check your windshield. 393.78A-WS appeared in 133 shared inspections in the last 90 days. A cracked windshield draws a close look at the whole vehicle.
- Carry and present annual inspection paperwork. 396.17C-PI — No proof of periodic inspection — appeared in 162 shared inspections. If you cannot show a current inspection sticker or documentation, an inspector has reason to look harder at every component, including coupling hardware.
- Freightliner drivers pay extra attention. Our data shows 3,043 of the all-time 393.55C2-B citations involved Freightliner tractors, far more than any other make. That does not mean Freightliners are defective — it reflects fleet size — but it means if you are driving one, you are in the most-cited group and your pre-trip coupling check needs to be thorough and documented.