ICD-10-CM > S00-T88 > T51-T65 > T58 > T58.9 > T58.91 T58.91 Toxic effect of carbon monoxide from unspecified source, accidental (unintentional) Non-Billable/Non-Specific Codes T58.91XA..., initial encounterT58.91XD..., subsequent encounterT58.91XS..., sequela