E12
Alpha
Ignition Lockout (Too Many Failed Attempts)
Furnace displays E12; inducer and blower may run but burners do not ignite.
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Repeated ignition failures due to bad igniter, No gas supply to furnace, Flame sensor not detecting flame, Control board lockout timer active
How to Fix / Troubleshooting
Safety: If you smell gas, shut off gas supply and ventilate the area. Do not attempt to restart.
- Power reset: Turn off power to the furnace for at least 30 seconds to clear the lockout. Restore power and call for heat.
- Observe ignition sequence: Through the sight glass, watch for inducer start, igniter glow, gas valve click, and burner ignition. Note at which step it fails.
- Address root cause: If the igniter does not glow, see E02. If burners light but go out quickly, see E01/E11. If there is no gas sound or smell, verify the gas shutoff is open and contact your gas supplier if other appliances are affected.
Repeated E12 lockouts indicate an unresolved ignition or flame-sense problem that should be professionally diagnosed.
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Repair Difficulty
Medium
3/5
Required Part
Alpha Integrated Furnace Control Board
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