York, Coleman Furnace Error Codes
Look up error codes to identify furnace problems and estimate repair costs.
Locating the furnace error code
Refer to the furnace glossary if you need help identifying furnace parts or terms.
All high-efficiency furnaces and most mid-efficiency furnaces show error codes on the control board, either as a flashing LED sequence or on a display .
The furnace control board is almost always in the lower compartment. You can view the error code LED or display through a small, clear plastic inspection port in the centre of the lower furnace cover.
If the control board isn’t in the lower compartment, it’s in the upper compartment.
Furnaces with upper and lower furnace covers — The inspection port is usually on the lower furnace cover and is accessible without removing the cover.
Furnaces with a one-piece front cover — Remove the front cover first. The inspection port is usually on the secondary cover for the lower compartment.
If the control board is in the upper compartment — You need to remove the upper furnace cover. If there are thumb screws, loosen them and pull the cover out from the screw location. If there are no screws, slide the cover straight up, then pull it out.
Don’t turn off the power to the furnace while troubleshooting — unless instructed otherwise. Turning off the power clears the current error code.
Observe the flashing LED sequence or display code, which may repeat in a loop. Watch it carefully, make note of the sequence or digits, and match it up with the corresponding code below:
4 amber flashes
Improper thermostat wiring
Possible faulty wiring or thermostat. Professional diagnosis required.
Rapid red flashing
Twinning error, incorrect 24V phasing
Possible wiring problem. Professional diagnosis required.
3 red flashes
Pressure switch stuck in open position
5 red flashes
Roll out switch open
Blocked exhaust or secondary heat exchanger, or faulty inducer motor. Professional diagnosis required.
9 red flashes
Grounding or polarity issue
Possible faulty control board. Professional diagnosis required.
10 red flashes
Gas continues to flow with gas valve closed
Possible faulty gas valve. Professional diagnosis required.
11 red flashes
Limit switch open for more than five minutes
Possible faulty blower motor. Professional diagnosis required.