York 5 Flashes Error Code
Flame loss — an established flame dropped out five times during one heating cycle (lockout).
Source: York 3/York_INSTALLATION-MANUAL-ZX-A7-08-TO-14-SER_InstallationGuide_HVAC_EN-5513316-uim-c-0819.pdf
What does York 5 Flashes mean?
Five flashes means a flame that was established during ignition was then lost: the flame signal dropped below 0.2 microamps five times within one heating cycle. After the fifth loss the gas valve relay opens following a five-second inducer post-purge and operation is inhibited. The control resets by cycling first-stage heat, cycling 24 VAC power, or after the 60-minute watchdog timer expires.
Symptoms
- Burners light but go out repeatedly during a heat call
- Furnace short-cycles before locking out
- ICB flashes a counted burst of 5 on the LED
- Inadequate or intermittent heat output
Common causes
- Weak or contaminated flame sensor (≈1/8" gap to the right burner)
- Marginal gas supply or low manifold pressure
- Poor grounding causing erratic flame signal
- Dirty burners or air in the gas lines
- Wind, water, or a heat-exchanger breach disturbing the flame
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Diagnostic steps
Inspect the flame sensor
Verify the flame sensor is intact and positioned with an approximate 1/8-inch gap to the right burner; clean a contaminated sensor.
Verify gas delivery
Confirm the gas lines are purged of air, inlet pressure is correct, and the gas valve provides proper manifold pressure.
Check grounding
Verify proper grounding and that the 24 VAC common and cabinet ground references are intact, since a weak ground destabilizes the flame signal.
Clean the burners
Confirm the burners are clean and free of blockages that could interfere with steady combustion.
Seal the heat compartment
Verify there is no wind, rain, or snow entering the compartment and no air leaks or heat-exchanger breaches disturbing the flame.
When to call a professional
Repeated flame loss points to a flame-sensing, gas-delivery, or combustion problem that usually needs a micro-amp meter and manometer to diagnose. If cleaning the sensor and confirming gas pressure do not stop the dropouts, call a licensed HVAC technician. Because flame instability can indicate a cracked heat exchanger or venting fault, a professional should inspect combustion and the heat exchanger before the furnace is returned to normal service.
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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).
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).
Gas valve miswire or gas valve relay fault — unexpected or missing 24 VAC at the gas valve outputs.