What 393.207F-SDAS means in plain language
This violation is issued when an inspector finds that one or more air bags in a vehicle's air suspension system have lost pressure — essentially a deflated or collapsed air spring that is no longer doing its job of supporting the load and cushioning the ride.
Air suspension systems rely on pressurized air bags to maintain proper ride height, distribute weight evenly across axles, and keep the vehicle stable under load. When one of those bags deflates, the frame can drop, axle alignment shifts, and the vehicle's handling changes in ways that affect braking, steering, and tire wear all at once.
This is not a paperwork issue or a minor equipment note. It is a structural condition that inspectors are trained to spot visually — a sagging corner, an uneven ride height, or a bag that has bottomed out against its bump stop. If an inspector sees it at roadside, the citation follows immediately.
What our enforcement data actually shows
The numbers here are stark. Across our database of 13 million+ inspections, 393.207F-SDAS carries a 96.1% out-of-service rate — meaning that in 6,763 of the 7,039 all-time citations on record, the driver was placed out of service on the spot. Only 276 citations resulted in no OOS action. To put that in context, the all-FMCSR average OOS rate across all codes is 31.4%. This code runs more than three times that average.
The code is ranked #284 out of 3,036 FMCSR codes by citation volume, which tells you inspectors encounter this condition regularly — it is not a rare or obscure finding. In the last 12 months alone, our inspection records show 4,332 citations issued under this code. In just the last 90 days, 908 citations were recorded.
Looking at monthly trend data, enforcement peaked at 509 citations in August 2025 and has remained consistently elevated, with October 2025 producing 447 citations and February 2026 producing 394. There is no quiet season for this violation — the data shows it is cited heavily year-round.
If you are reading this after being cited, the realistic picture is this: nearly every driver cited for 393.207F-SDAS is placed out of service. You will not be moving that vehicle until the air bag is repaired or replaced and pressure is restored.
Who gets cited most
Our inspection records for the last 180 days show California leading all states with 362 citations, followed by Michigan with 289 citations and Missouri with 140 citations. Georgia and Tennessee round out the active enforcement picture with 99 and 91 citations respectively.
The OOS rate variation across these states is worth noting. California's rate comes in at 90.6% — still extremely high, but measurably lower than Michigan's 98.6% and Missouri's 100.0%. Georgia, Tennessee, Ohio, South Carolina, Washington, Oregon, and US territories all showed 100.0% OOS rates in the same period. In practical terms, if you are operating in Michigan, Missouri, or most of the South and West, the data in our database indicates you should assume that any deflated air bag found at inspection means an immediate OOS order.
Among carriers, our data shows fleets such as Western Express Inc (USDOT 511412) with 34 all-time citations and Schaendorf Custom Farming Inc (USDOT 1107794) with 32 citations appearing most frequently in our records. New Prime Inc (USDOT 3706) follows with 24 citations. These numbers reflect that high-mileage operations across diverse equipment encounter this condition across the full range of fleet types.
On the equipment side, Freightliner units account for 1,451 all-time citations — the highest of any make — followed by FRHT at 1,042 and Volvo at 548. Kenworth appears at 542. If you run any of these makes, your pre-trip air suspension check is not optional.
How severe is this compared to similar codes
Within the Vehicle Maintenance category, the contrast with peer codes is dramatic. Take 393.9(a) — Inoperable required lamps — which has accumulated 660,737 citations but carries only a 15.4% OOS rate. Or 396.3(a)(1) — Inspection, repair, and maintenance general — with 236,919 citations and a 45.3% OOS rate. Even that 45.3% rate, itself above average, is less than half of what 393.207F-SDAS delivers at 96.1%.
Another peer, 396.17C-PI — No proof of periodic inspection — has 212,081 citations but a 0.0% OOS rate, meaning inspectors write it up but almost never park the truck for it. The deflated air suspension code sits at the opposite extreme: lower volume but near-certain OOS consequences when issued. If you are trying to rank which maintenance failures carry the most immediate operational risk, 393.207F-SDAS belongs at the top of that list.
How to avoid it
The co-occurring violation pattern in our data tells a clear story about what else breaks down on trucks that get cited for deflated air suspension. Here is what to check on every pre-trip:
- Walk the suspension visually before you move. Look at ride height at each corner of the trailer and tractor. A bag that has lost pressure overnight will show as a visible sag. Our data shows 393.75A3-TAOL — tires with inflation below 50% of maximum — appears in 107 of the same inspections as this code. A deflated bag and a flat tire often arrive together.
- Listen to the system build. At key-on, verify the air system builds to operating pressure and holds. If a bag has a slow leak, pressure loss may be detectable before you pull out.
- Check slack adjusters during every pre-trip. 393.47E — slack adjuster defective — appeared in 64 shared inspections in our 90-day data. A truck with a collapsed air bag is also a truck that may be out of brake adjustment, because ride height affects brake geometry.
- Know your brake OOS threshold. 396.3A1-BOS — brakes out of service due to 20% or more defective service brakes — appeared in 60 shared inspections. These failures cluster together. If you find the air bag is down, assume the brakes need a full check too.
- Verify coupling devices and hoses. 393.55E-B — coupling device or towing method defective — and 393.45D-B — brake tubing and hoses inadequate — each appeared in 48 and 44 shared inspections respectively. Inspect air lines and hose connections at the suspension bag for cracking, chafing, or fittings that are no longer seating properly.
- Freightliner and Volvo operators: inspect bag mounts specifically. With Freightliner units accounting for 1,451 all-time citations and Volvo at 548, drivers on these platforms should add a direct tactile check of the bag and its mounting bracket to their routine — not just a visual pass from a distance.
- Flag it during the pre-trip, not at the scale. Once an inspector sees a deflated bag, the OOS order is almost certain. Our 96.1% all-time OOS rate leaves almost no room for a warning and a wave-through.