Abbreviation: OOS
Out-of-Service Order
An order that prohibits a CMV driver or vehicle from operating until cited safety violations are resolved, issued during roadside inspections.
Driver OOS violations (such as excessive HOS violations or expired medical certificates) immediately prohibit the driver from operating. Vehicle OOS violations (such as brake or tire defects) prohibit the vehicle from operating until repaired. OOS events are recorded in FMCSA's MCMIS system and affect carrier CSA scores and driver PSP records.
Driver OOS vs. vehicle OOS
OOS orders can apply to the driver, the vehicle, or both independently. Driver OOS conditions include: HOS violations exceeding driving limits, expired or invalid CDL, expired DOT medical certificate, and a positive alcohol test at roadside. Vehicle OOS conditions include brake defects above the OOS threshold, tire failures, unsafe cargo securement, and critical lighting failures. A driver can be placed OOS while another qualified driver takes the vehicle, and vice versa — they are separate determinations.
OOS impact on PSP and CSA
OOS orders are stored in FMCSA's MCMIS database. For drivers, OOS violations appear on their PSP report for 3 years and can affect hiring decisions. For carriers, OOS events carry higher severity weights in the relevant CSA BASIC — a Vehicle Maintenance OOS order counts more heavily than a non-OOS violation. The combination of the operational disruption, potential fines, and lasting score impact makes OOS avoidance one of the most concrete ROI cases for compliance investment.
Last updated: May 28, 2026
When this definition matters
This term usually matters when a driver, owner-operator, or small carrier is deciding whether a federal rule applies, preparing a compliance file, or checking a state CDL step. Use this definition as a starting point, then confirm the controlling requirement in the official source listed below before making a licensing, hiring, dispatch, or recordkeeping decision.
The related terms above are included because they often appear in the same compliance workflow. Reviewing them together can prevent common mix-ups, such as treating a state licensing step as a federal carrier obligation or confusing a driver record with a separate employer record.