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.
Last updated: May 28, 2026