York furnace 2 amber flashes: Normal operation with a call for second stage heat
Two amber flashes means the furnace is running normally on second stage heat. It is a status indication rather than a fault.
Applies to: York, Luxaire and Coleman two-stage gas furnaces using the UTEC or W/R integrated furnace control boards documented in technical service letter ST-045-09. Single stage boards show this as not applicable.
What it means
Amber on these boards indicates heating status, and two amber flashes means a second stage heat call is present and the furnace is running at its higher firing rate. This is normal operation in cold weather, when first stage alone cannot keep up. Seeing it is mildly reassuring on a two-stage furnace: it confirms the furnace can reach high fire, which rules out the second stage pressure switch faults that leave a furnace stuck on low. The reason it deserves noting is the collision with two red flashes, which is a pressure switch stuck closed — same count, entirely different meaning.
Most common causes
- The thermostat is calling for second stage heat and the furnace is responding. This is normal.
- Cold weather demanding more output than first stage can provide.
- The furnace stepping up after running on first stage without satisfying the thermostat.
How to diagnose it
- Confirm the colour is amber and not red, since two red flashes is a pressure switch fault.
- Note whether the furnace is actually producing heat, which confirms the indication matches reality.
- Note whether the furnace reaches second stage only in genuinely cold weather, which is expected behaviour.
- If the furnace runs on second stage constantly in mild weather, that may indicate a staging or configuration issue worth mentioning at the next service.
How to fix it
- Nothing to fix. This is normal operation.
- If the house is not keeping up even on second stage, check the air filter and registers before assuming a furnace fault.
- If the furnace never reaches second stage in cold weather, look for a second stage pressure switch fault instead.
- Learn what normal looks like on your own furnace while it is working.
Notes
A two-stage furnace reaching second stage in cold weather is doing exactly what it was designed to do. Constant second stage operation in mild conditions is more worth asking about, since it suggests the furnace is not staging as intended.
Related
All codes for this manufacturer
York, Luxaire and Coleman furnace flash codes — every code, with what differs between models.