York 10 Flashes Error Code
Gas valve miswire or gas valve relay fault — unexpected or missing 24 VAC at the gas valve outputs.
Source: York 3/York_INSTALLATION-MANUAL-ZX-A7-08-TO-14-SER_InstallationGuide_HVAC_EN-5513316-uim-c-0819.pdf
What does York 10 Flashes mean?
Ten flashes flags a gas valve circuit fault with two possible causes. Either a miswire: 24 VAC was present for more than one second at the first- or second-stage gas valve output (P1-7 or P1-4) when the valve was commanded off. Or a relay fault: 24 VAC was not sensed for more than one second at those outputs when the valve was commanded on. The control opens its output relay to inhibit operation.
Symptoms
- Furnace fails to fire on a call for heat, or behaves erratically
- ICB flashes a counted burst of 10 on the LED
- Inducer may run to purge after the fault is detected
- No reliable gas-heat operation
Common causes
- Gas valve wiring shorted so 24 VAC from another circuit reaches the valve outputs
- Miswired first- or second-stage gas valve connections
- Control's first-stage (P1-8 to P1-7) or second-stage (P1-7 to P1-4) relay contacts shorted
- Control relay contacts that fail to close when commanded on
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Diagnostic steps
Inspect gas valve wiring
Verify the wiring from the ignition control to the gas valve is intact and not shorted in a way that would apply 24 VAC from another circuit to the P1-7 or P1-4 outputs.
Confirm correct connections
Verify the first- and second-stage gas valve outputs are wired to the correct terminals and not crossed.
Test the relay contacts
Verify the control's first-stage (P1-8 to P1-7) and second-stage (P1-7 to P1-4) gas valve relay contacts are not shorted and do not fail to close when commanded on.
Power-cycle the control
Cycle 24 VAC power to the ignition control to clear the fault after the wiring or relay issue is corrected.
When to call a professional
A ten-flash code involves the gas valve control circuit, where a wiring short can apply power to the valve unexpectedly — a gas-safety concern. A licensed HVAC technician should trace the gas valve wiring with a meter and, if the wiring is correct, determine whether the control's relay contacts have failed and replace the board. Do not bypass the fault or return the unit to service until the gas valve operates only when commanded.
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Other York Error Codes
Normal operation — the ignition control board is powered and ready to respond to a heating demand.
LED is steady off — no power to the control, or the control has suffered catastrophic damage.
LED is steady on — the control's microprocessor has not passed its self-check.
Induced draft pressure switch did not close — the switch failed to prove airflow within 10 seconds of the inducer starting.
Induced draft pressure switch stuck closed — the switch reads closed at the same moment a call for heat begins.
Flame could not be established — no flame was sensed in three consecutive ignition attempts (lockout).
Flame loss — an established flame dropped out five times during one heating cycle (lockout).
Open limit — 24 VAC was lost at the limit-switch input for six minutes or less during a call for heat.
Open rollout — 24 VAC was lost at the control's flame rollout switch input.
Gas valve failed to shut off — flame was sensed for more than 2 seconds after the gas valve output was turned off.
Indoor airflow failure / open limit — limit input lost 24 VAC for more than six minutes during a call for heat (hard lockout).