What 393.207(g) means in plain language
FMCSR 393.207(g) addresses the air suspension exhaust control system on your truck. This component manages airflow and pressure regulation in your air suspension setup. When an inspector cites you for this code, they've identified that the exhaust control is either missing or not functioning as required.
Air suspension systems rely on properly functioning exhaust controls to maintain vehicle stability and prevent unintended suspension collapse during operation. A defective or missing exhaust control can lead to unpredictable suspension behavior, which affects your load stability and braking performance. The regulation requires that this control be present and operational whenever your truck is in service.
What our enforcement data actually shows
Across our 13 million+ inspection records, 393.207(g) citations are uncommon. We've recorded 185 all-time citations for this code, with zero citations in the last 12 months and zero in the last 90 days. This places 393.207(g) at rank #1238 out of 3,036 FMCSR codes by citation volume.
When cited for 393.207(g), your risk of being placed out of service is low. Our data shows a 2.2% out-of-service rate for this violation. This is significantly below the all-FMCSR average OOS rate of 31.4%, indicating that inspectors typically do not remove trucks from service for this defect. Of the 185 citations in our database, only 4 resulted in an out-of-service order, while 181 were issued as violations without service removal.
The near-zero enforcement volume in recent months suggests that either the defect is rarely encountered during roadside inspections, or carriers and drivers have made this component less of an enforcement focus across the industry.
Who gets cited most
Our inspection records do not break down 393.207(g) citations by state in a way that identifies a clear top-three geographic concentration. Instead, enforcement has been scattered. The carrier data shows that DYLKA DISTRIBUCIONES Y LOGISTIK SA DE CV (USDOT 2510372) appears in our records with 4 citations for this code, the highest count among carriers. Several other carriers including RAUL GALVAN FRAUSTO, TRANSPORTES MOR SA DE CV, JUAN CARLOS FLORES, and others each have 2 citations.
Vehicle make data reveals a pattern: FREIGHTLINER (FRHT) trucks represent 21 of the 185 citations, followed by Kenworth (KW) with 16 citations and Peterbilt (PTRB) with 12 citations. If you operate a Freightliner or similar heavy-duty tractor, your pre-trip inspection should pay particular attention to the air suspension exhaust control.
How severe is this compared to similar codes
When measured against peer codes in the Vehicle Maintenance category, 393.207(g) stands out for its rarity and low enforcement rate. For comparison:
393.9(a) — Inoperable required lamps has generated 660,737 citations with a 15.4% OOS rate. Lighting violations are cited far more frequently and result in out-of-service orders more often than air suspension exhaust control defects.
396.3(a)(1) — Inspection/repair/maintenance general shows 236,919 citations and a 45.3% OOS rate, reflecting the serious nature of general maintenance violations and their high likelihood of roadside removal.
393.47E — Slack adjuster defective has 180,363 citations but a 0.0% OOS rate, making it comparable to 393.207(g) in its low removal frequency despite higher citation volume.
The comparison shows that while air suspension exhaust control defects are enforced less frequently than lighting or general maintenance failures, when they are cited, the resulting OOS rate is actually low—suggesting inspectors view these violations as correctable rather than immediately dangerous.
How to avoid it
Based on the vehicle makes most commonly cited and the nature of air suspension systems, implement these pre-trip inspection steps:
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Inspect the air suspension exhaust control component for damage or separation. On Freightliner, Kenworth, and Peterbilt tractors, locate the exhaust control device on the air suspension assembly and confirm it is physically secure and not cracked or deteriorated.
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Check for air leaks or hissing sounds near the suspension. A defective exhaust control often first signals itself through air loss. If your air pressure gauge shows a slow leak or you hear compressed air escaping from the rear axle area, address it before your next run.
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Verify that the exhaust control moves freely and is not blocked. The component must function without obstruction. Dirt, mud, or ice buildup can impede movement and trigger an inspection citation.
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Schedule preventive maintenance for your air suspension system annually. If your carrier operates Freightliner or Kenworth equipment, include air suspension exhaust control inspection in your preventive maintenance schedule to catch issues before they result in roadside citations.
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Document any repairs or replacements. If you or your maintenance team replace or service the exhaust control, keep records. Having maintenance documentation can support your defense if a citation is later disputed.