York LED Blink Codes

Line voltage polarity is reversed.

• Hot and neutral reversed at disconnect or outlet

1. Check outlet polarity
2. Correct wiring at disconnect switch

Gas valve circuit problem detected.

• Bad gas valve coil
• Board output failure
• Wiring damage

1. Test gas valve coil resistance
2. Check wiring to gas valve
3. Test board output voltage

System in lockout or retry mode due to failed ignition.

• Ignition failure
• Flame loss during run

1. Check gas supply
2. Clean flame sensor
3. Test igniter

Pressure switch has not closed or has opened during operation.

• Blocked vent
• Inducer issue
• Hose fault
• Condensate blockage

1. Inspect flue and intake pipes
2. Check pressure switch hose
3. Test inducer motor amps
4. Clear condensate drain

High limit or flame rollout switch has opened.

• Dirty filter
• Airflow restricted
• Flame rollout trip
• Blocked return

1. Replace air filter FIRST
2. Check all vents
3. Check rollout switches
4. Inspect heat exchanger if rollout tripped

Board fuse blown or flame lost during heating cycle.

• Blown 3A fuse on board
• Short in low voltage circuit
• Flame sensor contaminated

1. Check board fuse
2. Inspect low voltage wiring for shorts
3. Clean flame sensor
4. Check thermostat connections

Flame detected when gas valve is off.

• Leaking gas valve
• Board malfunction

1. SAFETY: Turn off gas immediately
2. Test gas valve for leak-through
3. Replace gas valve if confirmed

The control board has failed its internal self-test diagnostic.

• Control board failure
• Power surge damage
• Component aging

1. Power cycle furnace (wait 30 seconds)
2. If persists, replace control board
3. Check for proper voltage to board

System is in standby. No thermostat call active.

1. No action needed — normal standby

System has received a call for heat and is operating normally.

1. No action needed — system is running