York furnace Solid LED: Control fault detected
A steadily lit LED of any colour means the control has detected a fault in itself. York notes that solid LED error codes are not included in the stored fault code replay.
Applies to: York, Luxaire and Coleman gas furnaces using the UTEC integrated furnace control boards documented in technical service letter ST-045-09. York specifies a solid LED of any colour indicates this condition.
What it means
York's table specifies that a solid LED of any colour indicates a control fault detected — the colour does not narrow it further, which is unusual and worth knowing. The board has found a problem within its own operation rather than in the furnace's mechanical parts. There is also a documented limitation that matters practically: solid LED error codes are not displayed during fault code retrieval. So a control fault that has since cleared leaves no trace in the history, unlike the flash codes marked as stored in the error array.
Most common causes
- An internal control board fault.
- A microprocessor or internal check failure.
- Electrical damage to the control from a surge.
- Water damage to the control board.
- A control approaching the end of its service life.
- A supply problem the board's internal checks have flagged.
How to diagnose it
- Confirm the LED is genuinely steady rather than flashing, since heartbeat patterns on these boards are normal operation.
- Note that the colour does not matter — York specifies a solid LED of any colour indicates this condition.
- Note whether there was a recent power surge, storm, or electrical event.
- Check whether the furnace or its surroundings have been wet.
- Do not expect this to appear in the stored fault replay, since York documents that solid LED codes are not displayed.
How to fix it
- Try one power reset — off at the service switch for about thirty seconds, then on. A transient condition may clear.
- If the indication returns, the control board needs a technician.
- If the furnace has been wet, do not power it up. Have it inspected first.
- If a surge is suspected, consider whether surge protection is worth fitting, since replacing a board without addressing a recurring cause invites a repeat.
Notes
The exclusion of solid LED codes from the stored history is a real gap. An intermittent control fault leaves no record, which means noting the date and time when you see one is the only way it gets captured.
Related
- Fault code retrieval — How to read and clear stored fault codes on York UTEC boards
- Rapid red flashing — Twinning error or incorrect 24 volt phasing
All codes for this manufacturer
York, Luxaire and Coleman furnace flash codes — every code, with what differs between models.
What the fix costs
This is control board territory: $400–900 installed per the control board cost guide — $400–700 for a universal board, $500–900 for OEM. That guide's central warning is that boards are the industry's easiest part to blame and that many replaced boards were fine; a solid LED is the rare code where the suspicion is legitimate, because the board is reporting on itself. Even then, the guide's add-on is worth its $75–150: diagnosis of what killed the board. Boards rarely die of boredom — a surge, or water from a condensate leak dripping onto the traces, kills them, and a new board installed under the same drip dies the same way. The free step comes first: a single power reset costs nothing and clears a transient condition. One generation caveat with real money attached: on the last-generation White-Rodgers Emerson boards a solid red is an internal gas valve error rather than a generic control fault, which moves the conversation from a $400–900 board to a $300–900 gas valve. Check the board part number before anyone orders either part.
Fix it yourself or call a professional?
The homeowner move on this code is exactly one power reset — off at the service switch for about thirty seconds, then on. One, not several: a control fault that survives a reset is not going to yield to a dozen, and repeated cycling of a board that is reporting internal trouble proves nothing. If the solid LED returns, it is a technician visit; if the furnace or its cabinet has been wet, skip the reset entirely and leave it unpowered until it is inspected. Because York documents that solid LED codes are excluded from the stored fault replay, your note of the date and time you saw it is the only record that will exist — write it down before it slips. The replacement itself, with its wiring harness transfer and configuration, is professional work, and so is the diagnosis of cause that should accompany it. Which board generation you have decides what the solid light even means, so settle that first.
The same fault on other brands
An integrated control reporting its own failure is one of the few code meanings that is broadly consistent across the industry: Carrier's status 45 (control circuitry lockout), Trane's E01 and its continuous-on indication (replace the integrated furnace control), Lennox's E163, and the Goodman GMEC96's solid red — that last one matching this code's UTEC reading, though note York alone specifies that any colour held solid means the same thing. These are the codes where board replacement is legitimately on the table rather than a guess.
What this looks like
From the outside, this usually shows up as the thermostat screen is blank — that walkthrough covers what to check in order, and when it stops being a homeowner job.