York Furnace Light Blinking? Reading the Flash Codes
On many York furnaces the light's color is part of the message — green, amber, and red mean different families of news. Green usually reports normal operation, amber often relates to flame status, and red in counted bursts is the fault code. Count the flashes between pauses; that number is the code.
Safety first, every page: smell gas anywhere, skip everything below — leave the house and call your gas company from outside.
Before anything else
- Write down the color, the count, and your model number (sticker inside the cabinet). Cutting power erases the code.
- The legend for your exact model is printed inside the furnace door. The list below covers common meanings across many York (and Coleman and Luxaire — same family) models; the door sticker is the tiebreaker.
Common York codes
- Steady or slow-flashing green — normal. Powered and happy, or happily heating.
- Rapid amber flicker — often a weak flame signal: a dirty flame sensor barely seeing the burner. Runs today, quits soon. Cheap fix for a pro.
- Red, 2 flashes — pressure switch stuck closed. Pro call.
- Red, 3 flashes — pressure switch won't close: the furnace can't prove its vent is drawing. Check the outdoor vent pipes for snow, ice, leaves, or nests — the one genuinely free fix on this list.
- Red, 4 flashes — high limit tripped: overheating. Check the filter (hold it to a light) and open blocked vents.
- Red, 5 flashes — flame where there shouldn't be flame. Turn the system off and call.
- Red, 7–9 flashes — ignition or blower circuit trouble. Pro territory.
- Steady red — on many models, a lockout after repeated failures. One power cycle may buy another attempt; if it locks out again, call.
The free fixes, then one reset
Filter, vents, outdoor pipes. Then one reset only: power switch off 30 seconds, back on. If the code returns, resetting again fixes nothing and risks more — call instead, and lead with the color, the count, and the model number. That sentence alone makes you the best-prepared caller of the dispatcher's day.
Related symptoms
Start the free troubleshooter → Free, no sign-up, about ten minutes.
Start the free troubleshooter →Free · no sign-up · no personal info · about ten minutes