York furnace 10 red flashes: Gas valve energised with no call for heat
Ten red flashes means the gas valve is energised when no heating demand exists. The control is detecting power at the valve it did not command.
Applies to: York, Luxaire and Coleman gas furnaces using the UTEC integrated furnace control boards documented in technical service letter ST-045-09. Stored in the error code array.
What it means
This code is specifically about the electrical state of the gas valve rather than about detected flame. The control has found the valve energised with no call for heat, meaning something is powering it outside the intended sequence. That is a distinct fault from flame being sensed with the valve off, and the two together bracket the gas valve from both directions — one says gas is burning when it should not be, this one says the valve is being powered when it should not be. Either way the control cannot predict the valve's behaviour, so it stops.
Most common causes
- A failed valve relay on the control board, stuck closed.
- A wiring fault energising the gas valve circuit.
- A miswired gas valve, most often after recent service.
- A short in the low voltage wiring feeding the valve circuit.
- A control board fault driving the valve output incorrectly.
- A replacement gas valve wired differently from the original.
How to diagnose it
- Note any smell of gas and act on it immediately rather than continuing to diagnose.
- Do not open the burner compartment while the furnace is powered.
- Establish whether the furnace has been serviced recently, since a miswired valve does not develop on its own.
- Have the stored fault history replayed, since this code is retained.
- On last-generation White-Rodgers Emerson boards this count means gas actually flowing with no call for heat, not merely the valve being energised — the more serious of the two readings. Check the board part number.
How to fix it
- If you smell gas: leave the building, operate no electrical switches, and call your gas utility's emergency line or the fire service from outside.
- With no gas smell, switch the furnace off at its service switch and leave it off until a licensed technician has seen it.
- This is entirely technician work, involving the gas valve circuit.
- Do not reset repeatedly. The control has stopped because it cannot account for power at the gas valve.
Notes
Codes 1 and 10 on these boards approach the same component from opposite directions — one detects combustion that should not be happening, the other detects power that should not be present. A furnace showing both has a gas valve problem from any reading.
Related
- 1 red flash — Flame sensed with the gas valve off
- Solid LED — Control fault detected
- Which York control board you have — York used two control board generations with different code meanings
All codes for this manufacturer
York, Luxaire and Coleman furnace flash codes — every code, with what differs between models.
Not sure this is your brand?
The same count means something else on other furnaces. What 10 flashes means on every brand puts them side by side.
What the fix costs
The two parts this code implicates are the gas valve and the control board, and neither is cheap: a gas valve runs $300–900 per the furnace repair cost guide — which flatly calls it never a DIY part — and a board with a welded valve relay runs $400–900 installed. The wiring-fault version, a short powering the valve circuit or a miswire after service, is often little more than diagnostic labor at $75–150, usually credited. One cost note peculiar to this code: if it appeared right after a service visit, call the original company before paying anyone else. A miswired gas valve does not develop on its own, and correcting recent workmanship should be their bill, not yours.
Fix it yourself or call a professional?
There is no homeowner lane on this code. The control has found power at the gas valve that it did not command and cannot account for, which makes the furnace's most safety-critical component unpredictable. The furnace goes off at its service switch and stays off. The two useful things a homeowner does here are done from a safe distance: follow the gas-smell protocol if there is any smell — leave, touch no switches, call from outside — and recall the service history, since recent work on the furnace is the most common origin of a miswired valve circuit. Do not reset to see whether the code recurs. It is stored in the error array, so the board already keeps that record, and every retry is another unsupervised interval in which the valve circuit can do the wrong thing.
The same fault on other brands
The near-matching Goodman GMEC96 table shows how two boards can watch the same failure from different vantage points: its tenth code, 10 red flashes, reports gas flow detected — the physical event — where the UTEC board reports the electrical state, valve energised. The Emerson-generation York boards read like the Goodman wording too, as noted above, which fits the shared White-Rodgers lineage of those tables. Codes that police the gas valve's behaviour across brands are collected at the gas valve code index; the mirror-image fault, flame detected with the valve commanded off, is this board's 1 red flash.
What this looks like
From the outside, this usually shows up as the furnace turns over but never lights — that walkthrough covers what to check in order, and when it stops being a homeowner job.