1. What “out of service” means
An out-of-service (OOS) order is issued during a DOT inspection when a violation is serious enough that continued operation would be an imminent hazard. The truck or driver cannot legally move until the problem is corrected. OOS criteria are defined by the Commercial Vehicle Safety Alliance and applied uniformly across North America, so an OOS order means a defined safety threshold was crossed — not an inspector’s discretion.
2. Vehicle OOS vs driver OOS
A vehicle out-of-service order applies to the truck or trailer — for example, brakes out of adjustment beyond the allowable limit, a flat or exposed-cord tire, or steering and coupling defects. A driver out-of-service order applies to the person — an expired or suspended license, no valid medical certificate, or an hours-of-service violation. When you are evaluating a used truck, the vehicle OOS events are what reflect on the equipment.
3. The most common OOS violations
Brakes are the single most common vehicle out-of-service category — out-of-adjustment brakes, defective components, and inoperative systems. Tires are next: flats, exposed cords, and insufficient tread. Lighting, cargo securement, steering, and suspension round out the list. Knowing which system triggered the OOS tells you whether it was a quick roadside fix or a sign of deeper neglect.
4. Why repeat OOS events matter
A single out-of-service event can happen to any truck. A pattern is what should change your offer — or end the deal. Two or three brake OOS orders across a couple of years point to a maintenance culture that deferred safety repairs. Because the orders are tied to the VIN, that pattern follows the specific truck, not the carrier’s fleet average.
5. How OOS fits into CSA and SMS
FMCSA aggregates inspection and violation data into the Safety Measurement System, which scores carriers across categories such as Vehicle Maintenance and Unsafe Driving. For a used-truck buyer the carrier score is secondary; what matters is the individual truck’s violation and OOS record, which you read straight from its inspection history.
6. How to find a truck’s OOS history by VIN
Pull the truck’s DOT roadside-inspection history by its 17-character VIN and look at the out-of-service column. TruckWhere surfaces these events free by VIN, and its $19.99 DOT Roadside History & Buyer Report flags repeated-system detections so you do not have to read raw inspection codes yourself.
Buying a used semi or commercial truck?
Run the free TruckWhere VIN lookup first — you'll see whether FMCSA roadside records exist for that exact 17-character VIN. If meaningful records turn up, unlock the $19.99 DOT Roadside History & Buyer Report to see repeated-system issues, out-of-service events, the carriers observed operating the truck, seller questions, and a pre-purchase checklist.
TruckWhere is CarWhere's sister product for commercial-truck VIN & DOT roadside-inspection history.
Frequently asked questions
What is an FMCSA out-of-service violation?
It is a violation found during a DOT inspection that is serious enough to bar the truck or driver from operating until it is corrected. Out-of-service criteria are set by the Commercial Vehicle Safety Alliance and applied uniformly across North America.
What is the most common vehicle out-of-service violation?
Brake violations — out-of-adjustment or defective brakes — are the most common vehicle out-of-service category, followed by tire defects such as flats and exposed cords.
How do I see a specific truck’s out-of-service history?
Look up the truck’s DOT roadside-inspection history by its 17-character VIN. TruckWhere shows out-of-service events free by VIN; the $19.99 DOT Roadside History & Buyer Report highlights repeated-system patterns.
Sources
Primary sources behind the FMCSA, CVSA, and VIN-decoding claims on this page:
- NHTSA vPIC — VIN decoding — Federal 17-character VIN decoder (year, make, model, GVWR class).
- CVSA — North American Standard Inspection Program — Defines the roadside inspection levels (I–VI).
- CVSA — North American Standard Out-of-Service Criteria — The uniform thresholds that place a vehicle or driver out of service.
- FMCSA — Federal Motor Carrier Safety Administration — Roadside inspection regulations and the agency that records inspection results.
- FMCSA SAFER — carrier safety records — Carrier-level safety snapshot by USDOT number (distinct from VIN-level history).
- TruckWhere methodology — how inspections are matched to the exact VIN and unit (so a trailer defect is not blamed on the tractor).