ICD-10-CM > S00-T88 > T51-T65 > T59 > T59.2 > T59.2X > T59.2X4 T59.2X4 Toxic effect of formaldehyde, undetermined Non-Billable/Non-Specific Codes T59.2X4A..., initial encounterT59.2X4D..., subsequent encounterT59.2X4S..., sequela