York expanded error-code library

York furnace and heat pump codes

York furnaces report faults with blinking diagnostic lights or a code on the integrated control board; the number of flashes names the open safety switch or failed part. Always replace a dirty filter and check that vents and the condensate drain are clear before you look further. Gas, flame and overheating codes are for a licensed technician, who needs the model and serial number from the data plate.

York furnaces and heat pumps flash their codes on a control-board LED, counted as flashes with a pause between groups, and the code legend is usually printed on the inside of the furnace door. A furnace that shows a pressure-switch, flame-sense or limit-switch code has shut itself down for a safety reason, so the checks that matter are safe ones: replace a dirty filter, make sure every supply and return vent is open, check that the condensate drain is not backed up and look for snow or debris at the outdoor vent pipes.

Never bypass a safety switch to get heat back. A pressure switch proves the exhaust is venting, a flame sensor proves the burner lit, and a limit switch proves the furnace is not overheating. If the code returns after the safe checks, or if you smell gas, shut the furnace off at its switch and call a licensed technician. Note the model and serial number from the data plate before you call.