Comfortmaker Furnace Error Codes

The furnace ran through its ignition trials, never proved a flame, and locked out for safety. Many boards retry automatically after about an hour.

The furnace lit but the flame-sensing rod measured too little current, so the board closed the gas valve. The single most common furnace fault we see each winter in BC.

The inducer ran but the board never saw the pressure switch confirm draft, so it will not allow ignition — a venting safety interlock.

The board saw the pressure switch already closed before the inducer started, treats it as a fault, and refuses to fire.

The high-limit opened because the heat exchanger got too hot — almost always an airflow problem you should not ignore.

Safety-critical: flame rolled out of the burner box instead of drawing into the heat exchanger, tripping the manual-reset rollout switch. The furnace must be diagnosed by a technician before reset.

The board senses flame when the gas valve should be closed — a serious gas-control fault that locks the furnace out.

The furnace cannot run the inducer or main blower as commanded and shuts down — both are essential for safe operation.