What 393.68 means in plain language
This regulation requires that any compressed natural gas (CNG) fuel container installed on your commercial truck must meet specific federal standards for construction, testing, and installation. The container itself—the physical tank holding the CNG—must be manufactured, inspected, and maintained according to DOT specifications. This includes the container's design, welds, valve systems, pressure ratings, and how it's secured to the vehicle.
If an inspector finds that your CNG fuel container does not conform to these regulations, you'll receive a 393.68 citation. This typically means the tank failed a visual or technical inspection, was improperly installed, lacked required certification markings, or showed signs of damage or deterioration that makes it non-compliant with federal standards.
What our enforcement data actually shows
Across our 13 million+ inspection records, 393.68 is an extremely rare citation. Our database shows only 4 all-time citations for CNG fuel container non-compliance, with 1 citation in the last 12 months and 0 citations in the last 90 days. None of these 4 citations resulted in an out-of-service order, giving this code a 0.0% out-of-service rate.
This is significantly lower than the all-FMCSR average out-of-service rate of 31.4%, which reflects that inspectors have rarely found violations severe enough to require immediate vehicle removal from service. The rarity of this citation also means it ranks #2480 out of 3,036 FMCSR codes by enforcement volume, placing it well below the most frequently cited vehicle maintenance violations.
Who gets cited most
Our inspection records show that CNG fuel container violations are distributed across a small number of carriers and are not concentrated in any particular region or fleet. The carriers cited include SERVICIO DE TRANSPORTE INTERNACIONAL Y LOCAL SA DE CV (USDOT 557341), MARTIN FRANCISCO CAMPOS PEREZ (USDOT 643366), SHF TRUCKING LLC (USDOT 2385684), and 6 OAKS CONSTRUCTION INC (USDOT 3813698)—each with 1 citation in our database.
The vehicle makes involved in the citations we've recorded include International (2 citations), Kenworth (1 citation), and Utility (1 citation). This small sample size reflects the specialized nature of CNG fuel systems, which are less common than conventional diesel or gasoline engines in the trucking fleet.
How severe is this compared to similar codes
When we compare 393.68 to peer codes in the Vehicle Maintenance category, the contrast is stark. The most frequently cited peer code is 393.9(a)—inoperable required lamps—with 660,737 citations and a 15.4% out-of-service rate. Another high-volume peer code is 396.3(a)(1)—inspection/repair/maintenance general—with 236,919 citations and a 45.3% out-of-service rate.
Codes like 396.17(c)—no proof of periodic inspection—show 198,331 citations with a 0.0% out-of-service rate, similar to 393.68's enforcement profile. However, the raw volume difference is enormous: 393.68 has generated only 4 citations compared to 198,331 for 396.17(c). This underscores that CNG fuel container violations are exceptionally uncommon in roadside enforcement.
How to avoid it
If you operate a CNG-powered commercial truck, protect yourself against 393.68 citations with these driver-actionable steps:
-
Verify your tank certification before every trip. Before you start driving, confirm that your CNG fuel container displays current DOT certification markings and labels. These markings indicate the tank has passed required inspections and meets federal pressure and construction standards.
-
Inspect the container for visible damage or leaks. During your pre-trip inspection, walk around the tank and look for dents, cracks, corrosion, bulging, or any sign of leakage. A compromised container is a safety hazard and will fail inspection.
-
Check all mounting hardware and straps. Ensure the tank is securely fastened to the vehicle frame with all bolts tight and straps intact. Loose or missing fasteners can cause the tank to shift during transit, leading to a violation.
-
Know your tank's pressure rating and test date. CNG containers must be retested at prescribed intervals. Confirm the last retest date is within the allowable window. An expired retest date will trigger a citation.
-
Have a qualified technician service your CNG system. Do not attempt repairs or modifications to the fuel container or its connections yourself. Any work on a CNG system must be performed by a technician certified to work with pressurized fuel systems.
-
Maintain clear access to valve inspection points. Inspectors need to see the valve assembly and any safety relief devices clearly. Keep the area around the tank clean and free of debris or coverings that might obscure these components.
Given the rarity of this citation in our data, compliance is achievable through routine pre-trip inspection discipline and using a qualified service facility for all CNG system work.