FMCSR 393.80(a) — Exhaust System Defective: Citations & OOS

No. Across our inspection records, 393.80(a) has never resulted in an out-of-service order—the OOS rate is 0.0%. All 286 citations on record were issued with the vehicle allowed to continue operating.

This contrasts sharply with the national FMCSR average OOS rate of 31.4%, making 393.80(a) one of the least severe violations in the vehicle maintenance category. You will receive a citation, but your truck will not be impounded or prohibited from the road.

A single 393.80(a) citation carries a CSA severity weight of 4 points. These points roll into your carrier's Safety Management System (SMS) report and feed the Safety, Fitness, Improper Maintenance (SAFR) BASIC category.

The actual impact on your carrier's CSA score depends on the 30-day rolling average: if your carrier has multiple violations in a 30-day window, the point weight multiplies. A single isolated citation of 4 points is manageable, but patterns matter.

Immediate steps:

1. Document the defect: Take photos of the exhaust leak, loose mounting, or underslung discharge noted by the inspector.
2. Repair immediately: Schedule service with a qualified technician. This is a maintenance item, not a structural failure—most shops can resolve it within days.
3. Get proof of repair: Request an invoice showing the exhaust component was replaced or re-secured.
4. Notify your carrier: Report the citation and repair completion to your fleet's safety manager for CSA tracking.
5. Request a re-inspection (optional): If your carrier wishes to formally clear the violation, a roadside re-check can confirm repair compliance.

Since the OOS rate is 0.0%, you have time to arrange repairs without emergency downtime.

No, 393.80(a) is among the least serious maintenance violations. Our data shows:

• 393.80(a) OOS rate: 0.0%
• National FMCSR average OOS rate: 31.4%
• Peer codes in the same category: Inoperable lamps (393.9) have a 15.4% OOS rate; brake adjuster defects (393.47E) have 0.0%, matching yours; general inspection failures (396.3) spike to 45.3% OOS.

The exhaust defect is treated as a correctable maintenance item rather than a safety-critical failure. Repair the leak or loose mounting, and the issue resolves.

Yes. DataQs is the FMCSA's online system for contesting roadside inspection records. You can challenge a 393.80(a) citation if:

• The defect was not actually present (factual error by the inspector).
• The repair was completed before inspection (documentation issue).
• The measurement or method was incorrect (e.g., exhaust position measured wrong).

DataQs submissions typically take 30–45 days for review. If successful, the citation is removed from your CSA record. However, if the exhaust defect genuinely existed, the citation will stand. Gather repair invoices and photos as supporting evidence before filing.

Our inspection records show 286 total 393.80(a) citations across all states since record-keeping began. The enforcement volume is extremely low—zero citations in the last 12 months and zero in the last 90 days—so state-by-state clustering is minimal.

The citation appears scattered across small carriers and owner-operators rather than concentrated in specific high-traffic corridors. This suggests exhaust defects are caught opportunistically during routine inspections rather than being a targeted enforcement focus in any particular region.

Moderately urgent, but not emergency-level. The data shows zero out-of-service placements for 393.80(a), meaning inspectors do not consider the defect grounds for immediate removal.

However, zero citations in the last 90 days suggests the violation has fallen out of focus at roadside. Don't delay repair: a re-inspection by another officer could still flag it, and exhaust leaks worsen over time. Schedule service within 1–2 weeks. Most exhaust repairs (re-securing clamps, patch welding, or component replacement) take a few hours and cost $200–$800.

The violation follows both in the FMCSA's Safety Management System. The citation is recorded on the carrier's profile (affecting fleet safety ratings and potential intervention thresholds) and on the driver's record (affecting your personal CSA BASIC scores, particularly Safety and Improper Maintenance).

If you move to a new carrier, the citation stays attached to your record for the full five-year CSA lookup window. Your new employer will see it during the hiring process or CSA review.