10 red flashes Gas valve powered with no heat call

What the control is telling you

The gas valve is energized when there is no call for heat. The blower and inducer run and no ignition happens until it clears.

Applies to: York/JCI residential gas furnaces: York UTEC IFC furnaces, York White-Rodgers IFC furnaces, York TM9V

Likely causes

• Gas valve miswired
• Shorted valve wiring
• Board relay welded

Test and repair steps

1. Warning: Turn off the gas supply if the valve is open without a call.
2. Check gas valve wiring for shorts or miswiring.
3. Check the gas valve itself.
4. Replace the board if it is driving the valve with no call.
5. To read stored codes with no thermostat call active, tap the LAST ERROR button briefly (under 5 s); up to five codes play back newest first. Two green flashes = memory empty. Hold the button 5 s or more to clear (three green flashes confirm).

Settings for these units

Clearance to combustibles · York TM9V

Leave about 24 in. at the front and 18 in. at the side for service.

Approved for alcove and attic installs.

Filter size by return location · York TM9V

Sizes assume high velocity filters (600 FPM); throwaway filters must stay at or below 300 FPM.

Filters go outside the cabinet - never inside the furnace.

Models that show this code

7 models in York UTEC IFC furnaces, York White-Rodgers IFC furnaces, York TM9V

Other codes on the same units

• 6 red flashes Pressure switch cycling lockout
• 7 red flashes Ignition failure lockout (retries)
• 8 red flashes Flame lost repeatedly (recycles)
• 9 red flashes Polarity reversed or bad ground
• 11 red flashes Limit open 5-15 minutes - blower failure
• 12 red flashes Hot surface igniter open / igniter failure
• 13 red flashes High-fire pressure switch open
• LED steady off Board LED dark - no power to control