This morning Thursday 12/17/20 at approximately 10:20am, Mohegan FD (volunteer and career) responded to Acorn Ln in the Hunterbrook Condos in Yorktown for a carbon monoxide detector activation. Upon arrival, firefighters found readings of approximately 300ppm of carbon monoxide on our meters at the front door. Firefighters quickly checked the residence and were informed by the homeowner that the CO detector that activated was in the basement. Readings of over 400ppm were found in the basement boiler room and members shut down the natural gas furnace and utilized exaust fans to ventilate the residence. Once ventilated, the investigation continued and with the assistance of Con Edison Gas, it appeared to be a malfunctioning furnace. A more thorough investigation was performed and the exaust pipe was found to be buried purpose in a pile of snow. This caused the exaust and carbon monoxide to back up into the condo unit from unable to ventilate properly. The neighboring condo units were checked with no reasons or issues. We would like to remind everybody to make sure no exaust pipes are buried which could lead to an carbon monoxide incident. Units operating were Car 2262, 2264, 2266, 2269, 22610, Engine 257, Ladder 10, Reacue 32, and Utility 80. All units cleared by 12pm. Yorktown Police Department also assisted on scene.