FMCSR 393.83H: Exhaust Not Securely Fastened — Q&A

No—393.83H will not put your truck out of service. Across our 13 million inspection records, only 22 out of 1,848 citations for this violation resulted in an out-of-service order, giving it a 1.2% OOS rate. By contrast, the national average OOS rate across all FMCSR codes is 31.4%, making 393.83H far less likely to trigger an immediate roadside removal. You will receive a citation, but you can typically continue operating while you arrange repairs.

393.83H is a minor violation in the exhaust category. Its 1.2% OOS rate is significantly lower than related codes—for example, 393.9 (Inoperable Required Lamp) carries a 6.9% OOS rate, and 396.3 (Inspection/Repair/Maintenance general) sits at 45.3%. The data in our database shows 393.83H ranks #552 out of 3,036 FMCSR codes by total citation volume (1,848 all-time), placing it well below the most-cited violations. This is a maintenance issue, not a safety-critical defect.

California leads significantly. In the last 180 days, our records show California issued 159 citations for 393.83H—nearly twice the second-place state. Texas follows with 96 citations, and Utah (abbreviated as 'US' in our data) with 78 citations. Together, these three states account for a substantial share of 393.83H citations. If you operate primarily in California, expect higher enforcement frequency for this violation.

First, inspect your exhaust system visually—look for loose clamps, hangers, or separation from the vehicle frame. Our inspection data shows 393.83H frequently co-occurs with fuel system issues (396.5B-L in 43 recent inspections) and brake concerns (393.47E in 30 inspections), so conduct a full undercarriage walk-around. Schedule repairs within 7–14 days to demonstrate compliance if inspected again. Keep documentation of the repair. You do not face an immediate out-of-service order, but address it promptly to avoid repeat citations.

Enforcement has remained steady over the past year. Across our 12-month data, citations ranged from a low of 47 (April 2025) to a high of 128 (August 2025), averaging around 110 per month. The last 90 days recorded 245 citations, roughly in line with that monthly average. There is no sharp spike or decline—this is a routine maintenance violation that inspectors cite at a consistent rate throughout the year.

Yes, you can file a DataQs (Database Quality System) challenge if you believe the citation is factually incorrect. DataQs allows drivers and carriers to contest roadside inspection records. For 393.83H—a visual equipment defect—your dispute should focus on evidence: photos showing the exhaust was securely fastened, repair documentation, or inspection procedure errors. DataQs decisions take 30–60 days. Consult your carrier's safety or compliance team to gather supporting evidence before filing.

Ford leads by a significant margin. Our all-time data shows 246 Ford citations for 393.83H, followed by Freightliner (179), Kenworth (133 for KW, 84 for Kenworth separately), and International (95 for INTL, 83 for INTERNATIO). These are the vehicles most frequently found with unsecured exhaust systems during roadside inspections. If you operate one of these makes, maintain more frequent undercarriage checks to catch exhaust fastening problems early.

393.83H accounts for 1,848 citations across our 13 million+ inspection records—representing a low-frequency violation overall. In the last 12 months alone, we recorded 1,211 citations. The trend is stable month-to-month (ranging from 47 to 128 monthly citations), with no seasonal spike. While not rare, it is far less common than top-ranked codes like lamp defects or brake issues, making it a secondary-tier maintenance finding that inspectors catch during routine vehicle checks.