What 397.15 means in plain language
FSCR 397.15 prohibits a specific fueling practice: running the engine while you're refueling a commercial motor vehicle that is transporting hazardous materials. The regulation exists because a running engine creates ignition risk in an environment where flammable vapors may be present—a combination that amplifies fire and explosion hazard during the refueling process.
This is a straightforward safety rule. Before you pull into a fuel pump with a hazmat load on board, shut the engine off. Keep it off until the pump nozzle is removed and the fuel door is closed. No exceptions for quick top-ups or time pressure.
What our enforcement data actually shows
Our inspection records show 397.15 is extremely rare in practice. Across 13 million inspections in our database, we have documented only 2 all-time citations for this violation. In the last 12 months, that number is 0 citations. In the last 90 days, still 0.
When a citation does occur, the consequences are severe. Our data indicates a 100.0% out-of-service rate—meaning every time this violation has been cited, the vehicle was placed out of service immediately. That rate far exceeds the all-FMCSR average OOS rate of 31.4%, underscoring how seriously enforcement treats fueling hazmat with the engine running.
By citation volume, 397.15 ranks #2651 of 3,036 FMCSR codes. The rarity of enforcement does not mean the rule is unenforced; it means most drivers and fleets comply.
Who gets cited most
Given only 2 all-time citations in our 13 million inspection records, geographic and carrier patterns are not material. Our data shows fleets such as TVS TRUCKING AND OILFIELD SERVICE LLC (USDOT 2392510) and JULIO RODOLFO GONZALEZ OLVEDA (USDOT 2927508) each with 1 citation. We cannot meaningfully rank states or identify trend carriers from so few incidents.
The takeaway is that this violation is distributed across isolated incidents, not concentrated in any region or carrier type.
How severe is this compared to similar codes
Within the Hazardous Materials category, 397.15 sits at the extreme end of the severity spectrum when it does occur—100% OOS rate—but applies to a far narrower set of circumstances than peer violations.
For comparison: general loading and unloading hazmat violations (177.834A-HMC) appear 3,954 times with a 99.2% OOS rate, and 177.834(a) shows 3,839 citations with a 97.9% OOS rate. Both are much more frequent but similarly serious when cited. Placarding violations (177.817(a)) occur 2,274 times with a 75.1% OOS rate. By contrast, some peer codes like 172.602(c)(1) (maintenance of Emergency Response information) have been cited 1,464 times with a 0.0% OOS rate, indicating lower severity.
The 100% OOS rate on 397.15—even with only 2 citations—places it in the highest-consequence tier of hazmat rules.
How to avoid it
This violation is entirely preventable by adhering to one habit:
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Engine off before fueling: Make stopping the engine part of your pre-pump checklist. The moment you approach the fuel bay, turn off the engine before you exit the cab. Do not restart until the fuel cap is sealed and you are clear of the pump.
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Train every refueling stop: Whether you are running a team, a solo, or a short haul with hazmat, treat engine-off as non-negotiable. If you're parked for 10 minutes, that's 10 minutes with the engine off.
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Check your vehicle's fuel system: Before accepting a hazmat load, confirm the fuel door opens and closes smoothly, the fuel cap seals properly, and there are no leaks around the fill point. A fuel system defect does not excuse running the engine, but a well-maintained system makes compliance frictionless.
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Communicate with your fleet safety manager: If you are new to hazmat hauling, confirm your company's fueling protocol in writing. Some fleets have additional policies—such as waiting for a spotter or a fuel attendant—that go beyond the regulation. Knowing the expectation prevents confusion at the pump.
The regulation is not ambiguous, and enforcement does not tolerate exceptions. Engine off, fuel on, move on.