49 CFR §392.66

1. (a)No person shall dispatch or drive any commercial motor vehicle or permit any passengers thereon, when the following conditions are known to exist, until such conditions have been remedied or repaired:
   1. (1)Where an occupant has been affected by carbon monoxide;
   2. (2)Where carbon monoxide has been detected in the interior of the commercial motor vehicle;
   3. (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.
2. (b)[Reserved]