What 393.30-B means in plain language
This regulation requires that every battery on a commercial motor vehicle be mounted so it cannot shift or vibrate loose during normal operation. A battery that rattles around in its tray, is missing its hold-down hardware, or lacks appropriate covering where one is required is exactly what an inspector is looking for.
The rule exists for a straightforward safety reason: an unsecured battery can contact metal surfaces and create a short-circuit, a fire risk, or a complete electrical failure while the truck is moving. The covering requirement protects against accidental contact with the terminals.
In practice, this violation is almost always caught during a walkaround inspection. An inspector opens the battery compartment, gives the battery a quick push or pull, checks whether the hold-down bracket or strap is present and tight, and verifies that any required cover is in place. If anything is missing or loose, you get the citation.
What our enforcement data actually shows
The first thing to understand after getting this citation: you almost certainly kept rolling. Across all 11,621 all-time citations in our inspection records, only 4 vehicles were placed out of service — an OOS rate of effectively 0.0%. Compare that to the all-FMCSR average OOS rate of 31.4% across all codes in our database, and it's clear that 393.30-B is treated as a documentation and maintenance deficiency, not an immediate safety threat.
That said, the violation is far from rare. Our database ranks 393.30-B at #204 out of 3,036 FMCSR codes by citation volume — meaning roughly 2,800 codes get cited less often than this one. Over the last 12 months alone, our inspection records show 7,267 citations issued under this code. Zooming in further, 1,620 citations were recorded in just the last 90 days, which puts it on pace for continued high enforcement activity.
Looking at the monthly trend over the past year, citation counts have been consistently high — ranging from 563 in December 2025 to 691 in September 2025 — with no meaningful sign of inspectors backing off. This is a code that enforcement is actively writing, month after month.
Who gets cited most
Geographically, California is the dominant enforcement state by a wide margin. In just the last 180 days, our data shows 818 citations issued in California, compared to 365 at federal-level inspections (listed as US in our records) and 257 in New Jersey. Florida comes in close behind New Jersey with 256 citations in the same window, and Arizona follows at 205.
None of those top states show any meaningful OOS rate variation — all sit at 0.0% — so if you're operating across state lines, the citation risk is the primary concern, not a wildly different enforcement outcome depending on where you're stopped.
On the carrier side, our data shows fleets such as GUILLERMO ESQUER GARCIA (USDOT 3036898) with 27 all-time citations and AMPARO GUADALUPE BANDA GONZALEZ (USDOT 2515684) with 24 all-time citations appearing at the top of our records. No implication of negligence should be drawn from volume alone — larger operations with more vehicle movements naturally accumulate more inspections and, with them, more opportunities for any single deficiency to be caught.
In terms of vehicle makes, FREIGHTLINER units account for 1,732 all-time citations in our database — the highest of any make — followed by HINO at 1,075 and FORD at 866. ISUZU variants (recorded variously as ISU and ISUZU in our data) together account for another 1,562 citations. If you're operating one of these platforms, your battery compartment design and hold-down hardware deserve extra attention during pre-trip.
How severe is this compared to similar codes
Within the Vehicle Maintenance category, 393.30-B's 0.0% OOS rate stands in sharp contrast to several peer codes. Take 396.3(a)(1) — Inspection/repair/maintenance general — which our database shows has generated 236,919 citations at a 45.3% OOS rate. That single comparison illustrates how much heavier the consequences can be for broadly written maintenance failures compared to this specific, narrow battery-mounting issue.
Even 393.9(a) — Inoperable required lamps — which is an enormously common code at 660,737 citations in our records, carries a 15.4% OOS rate. A dead lamp is more than 15 times more likely to take your truck off the road than an unsecured battery.
For contrast in the other direction, 396.17C-PI — No proof of periodic inspection — sits at 212,081 citations and a 0.0% OOS rate, making it a closer behavioral parallel to 393.30-B: frequently cited, almost never a shutdown, but a CSA point burden that accumulates over time. With a CSA severity weight of 3, 393.30-B won't crater your safety score on its own, but repeated citations pile up.
How to avoid it
The good news is that this violation is almost entirely preventable with a thorough pre-trip inspection. The co-occurring violation patterns in our 90-day data point to something important: 393.30-B rarely shows up alone. It appears alongside 396.17C-PI (no periodic inspection proof) in 254 shared inspections, inoperable lamps codes in 223 and 171 shared inspections respectively, and windshield defects in 200 shared inspections. That pattern tells you this violation tends to cluster with general maintenance neglect — trucks that miss one thing tend to miss several.
- Check the battery hold-down hardware every pre-trip. Open the battery compartment and physically confirm the bracket, strap, or clamp is present and secure. A loose hold-down takes under a minute to tighten.
- Verify the battery cover is in place and undamaged. If your vehicle requires a cover over the terminals, make sure it hasn't cracked, warped, or gone missing since the last inspection.
- Look for signs the battery has shifted. Corrosion streaks on the tray sides, chafed cables, or a battery sitting unevenly in its mount are all indicators that movement has occurred.
- On FREIGHTLINER, HINO, FORD, and ISUZU platforms specifically, check that the hold-down hardware hasn't been stripped or substituted with the wrong hardware during a prior repair — these makes account for the highest citation volumes in our data.
- Don't let a loose battery be the start of a longer inspection. Our data shows 254 inspections where a 393.30-B citation was accompanied by a failure to carry proof of periodic inspection. Making sure your vehicle inspection paperwork is current reduces the odds that one defect turns into a full-vehicle teardown at the roadside.
- Use the co-occurring codes as a checklist. If your battery is loose, treat that as a signal to also verify your lamps (393.9A codes appear in 223 shared inspections), your windshield (393.78A in 200), and your fire extinguisher (393.95A1 in 157). A battery issue often signals a broader pre-trip routine that has slipped.