York 8 Flashes

What does York 8 Flashes mean?

Eight flashes means the first-stage gas valve failed to shut off: the control still sensed flame for longer than two seconds after it commanded the first-stage gas output off. The gas valve relay opens so gas operation is not permitted, and the inducer relay closes to run the inducer and purge residual gas. This protects against unintended gas flow. The code resets by cycling 24 VAC power to the control.

Symptoms

• Burners stay lit briefly after the control should have shut gas off
• Furnace locks out and will not restart normally
• ICB flashes a counted burst of 8 on the LED
• Inducer continues running to purge after shutdown

Common causes

• Gas valve slow to close or leaking by when de-energized
• Gas valve that does not fully shut off gas flow
• Gas valve wiring shorted so 24 VAC from another circuit reaches the valve
• Failed gas valve internal seat

Diagnostic steps

1. 01

   Observe valve shutoff

   Verify the gas valve is not slow to shut off, does not leak by, and fully stops gas flow when de-energized.

2. 02

   Inspect valve wiring

   Verify the gas valve wiring is intact and not shorted in a way that could improperly apply 24 VAC from another circuit to the valve.

3. 03

   Power-cycle the control

   Cycle 24 VAC power to the ignition control to clear the lockout after the fault is corrected.

4. 04

   Replace a leaking valve

   If the valve continues to pass gas when commanded off, replace the gas valve.

When to call a professional

A gas valve that does not fully close is a gas-safety hazard and should be handled by a licensed HVAC technician. Confirming whether the fault is the valve itself or a wiring short that backfeeds 24 VAC requires a meter and gas-pressure verification. Do not return the furnace to service until a professional has confirmed the valve seals completely and there is no unintended gas flow.