§393.83 sets the requirements for the exhaust system: no discharge of exhaust gases under the cab or sleeper berth; gasoline-engine exhaust must terminate beyond the body and not under any portion of the cab or body; diesel-engine exhaust must terminate to the rear of the cab. The system must be securely fastened. No part may be temporarily repaired with wrappings, patches, or fillers.
OOS criteria
An exhaust leak forward of or directly below the driver compartment or sleeper berth is OOS — carbon monoxide infiltration is the underlying risk. A leak anywhere on the system that allows accumulated exhaust gas to enter the occupied space is OOS.
Severity
Severity weight 3 in the Vehicle Maintenance BASIC. Pattern findings on the same vehicle indicate a deeper structural issue (manifold cracking, gasket failure, mounting-strap fatigue) that PM should be addressing.
How to prevent it
- DVIR pre-trip listens for exhaust changes; an unusual rumble at idle is the first sign of a manifold crack.
- §396.17 annual inspection includes a full-length exhaust-system visual inspection.
- Replace clamps and gaskets at every brake job; both are routinely overlooked.
How Roadworthy HQ helps
An exhaust citation shows up in Roadworthy HQ as part of the inspection it came from, not as a record of its own: the app does not store individual violation codes. Log the roadside inspection on the vehicle's Inspections tab: date, state, level, driver, the number of violations, and whether it was out-of-service. For an out-of-service inspection the 15-day §396.9(d)(3) repair-certification countdown stays on that tab until you enter the certification date. The rule's 15 days cover every violation on the report, not only out-of-service ones, so for a non-OOS inspection that date is yours to track. The repair itself goes in the vehicle's maintenance log: date, type, what was done, who did it, and cost. DVIRs are logged per vehicle with the defect described in your own words, and a defect marked safety-affecting that is logged without a repair certification sends a critical alert.