HVAC Code Lookup

York Furnace 5 Red Flashes

Safety faultShown as: Five red flashes, then a two-second pause, repeating

The normally closed flame rollout switch has opened. Flame or hot combustion gas has spilled out of the burner box instead of going up the vent. The control goes into a hard lockout that only a power cycle will clear.

Manual wording: “5 RED FLASHES: This fault is indicated if the normally closed rollout switch opens. The rollout control is manually reset. Check for proper combustion air, proper inducer operation, and primary heat exchanger failure or burner problem. The control will enter a hard lockout...”

Documented for: TG8S, TG9S, TM9E, TM9X, TM8X, TM9T, TM8T

Likely causes, most common first

  1. Insufficient combustion air
  2. Inducer not drawing properly
  3. Cracked or failed primary heat exchanger
  4. Burner problem

What you can safely check yourself

  • Check the outside vent and combustion air pipe terminations for blockage
  • Make sure nothing is stored against the furnace blocking its air supply
  • If you smell exhaust fumes or have any CO alarm activity, leave the house and call for service from outside

When to call a technician

Call a licensed technician before running the furnace again. A rollout trip means combustion gas escaped the burner compartment, which can mean a cracked heat exchanger and a carbon monoxide risk. The rollout switch is a manual-reset safety device and must only be reset by a technician after the cause is found.

A York furnace throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.

Sources

Other York codes