FMCSR 393.83A: Exhaust System Location Defects

Yes, very likely. Across our 13 million inspection records, 393.83A results in an out-of-service placement 87.3% of the time. That's nearly three times the all-FMCSR average OOS rate of 31.4%. In the last 90 days, 68 citations resulted in 59 OOS placements. Your truck can be towed or you may be prohibited from operating until the exhaust system is repositioned to prevent contact with wiring, fuel lines, or combustible parts.

This violation carries a CSA severity weight of 5 points. In your carrier's Vehicle Maintenance BASIC category, those points count toward a 30-day rolling window. The actual impact on your safety record depends on how many other violations your carrier accrued in the same 30-day period. A single 393.83A citation alone is serious, but your fleet's overall BASIC score is what determines whether your carrier faces intervention or training requirements.

1. Document the defect. Photograph the exhaust routing and its proximity to electrical, fuel, or other flammable components.
2. Do not operate. If placed OOS, the truck stays off the road until corrected.
3. Inspect related systems. Our data shows 393.83A often appears with slack adjuster defects (393.47E), fuel leaks (396.5B-L), and windshield damage (393.78A-WS). Have a mechanic check those too.
4. Get a repair invoice showing exhaust relocation and route documentation.
5. Request a re-inspection at the same facility or a certified weigh station.

Yes. While 393.83A is ranked #983 of 3,036 FMCSR codes by all-time citation volume (416 total), its 87.3% OOS rate is exceptionally high. Compare that to peer violations in Vehicle Maintenance: slack adjuster defects (393.47E) have a 0.0% OOS rate despite 180,363 total citations, and windshield defects (393.78) sit at just 0.3% OOS. Exhaust positioning that risks fire is treated as an immediate safety hazard, not a minor non-compliance.

You can submit a DataQs (Roadside Data Quality) challenge if you believe the inspection record contains factual errors—for example, if the inspector documented an OOS placement that never occurred, or misidentified your vehicle. However, disputes about whether your exhaust system actually poses a fire risk are engineering/safety questions, not data errors. Your best path is to get the exhaust repositioned, document the repair, and request a new inspection. Inspectors have discretion to note compliance once corrected.

In the last 180 days, Texas leads by far with 48 citations (83.3% OOS rate), followed by Utah and California, each with 6 citations (both 100% OOS). North Carolina had 3 citations with a 66.7% OOS rate. Texas accounts for nearly two-thirds of all recent 393.83A enforcement. If you operate heavy-haul or refrigerated units in that region, pay close attention to how exhaust headers and flexible piping are routed during pre-trip inspections.

Urgent. In the last 90 days, we've recorded 68 citations—averaging 2.3 per day. In February 2026 alone, there were 31 citations. The violation almost always triggers an OOS placement, meaning you lose revenue immediately and cannot legally operate until repaired. An exhaust system touching electrical or fuel components is a fire/electrical hazard under DOT rules. Repair typically involves moving or rerouting the exhaust pipe, which can be done at most truck shops in 2–4 hours.

Both. FMCSA records the violation against the carrier and vehicle in the Crash and Safety data (CSA), which affects your company's Vehicle Maintenance BASIC score. However, the driver is present at the time of the roadside inspection and responsible for pre-trip compliance. This citation does not go on your personal driving record—it goes on your carrier's safety profile and the vehicle's maintenance history. If the same truck is cited repeatedly, it reflects fleet maintenance practices, not driver performance.