ICD-10-CM > S00-T88 > T51-T65 > T58 > T58.9 > T58.94 T58.94 Toxic effect of carbon monoxide from unspecified source, undetermined Non-Billable/Non-Specific Codes T58.94XA..., initial encounterT58.94XD..., subsequent encounterT58.94XS..., sequela