Code of Federal Regulations Title 49. Transportation § 49.392.66 Carbon monoxide;  use of commercial motor vehicle when detected

(1) Where an occupant has been affected by carbon monoxide;

(2) Where carbon monoxide has been detected in the interior of the commercial motor vehicle;

(3) When a mechanical condition of the commercial motor vehicle is discovered which would be likely to produce a hazard to the occupants by reason of carbon monoxide.