Alpha
Alpha Furnaces Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
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E01
Furnace will not start; control board displays E01 immediately after a call for heat.
No Flame Detected on Ignition
E02
Furnace attempts to start but shuts down before ignition; E02 displayed on Alpha control module.
Ignition Failure / Igniter Fault
E03
Furnace starts, inducer runs, but burners do not light; E03 code appears after several attempts.
Gas Valve Not Energizing
E04
Furnace displays E04 and will not start; inducer motor does not run.
Inducer Motor Failure / Pressure Switch Not Proving
E05
Furnace starts but shuts down shortly after ignition; E05 displayed, blower may continue to run.
High Limit Switch Open (Overheat Condition)
E06
Furnace displays E06 and will not fire; inducer may start briefly then stop.
Pressure Switch Stuck Open
E07
Furnace shows E07; inducer runs continuously without ignition sequence starting.
Pressure Switch Stuck Closed
E08
Furnace displays E08; blower runs but burners do not light, or furnace shuts down mid-cycle.
Rollout Switch Open (Flame Rollout Detected)
E09
Furnace shows E09; blower may run continuously and burners will not ignite.
Low Temperature Limit / Freeze Protection Trip
E10
Furnace displays E10; no response to thermostat calls, control board LEDs may be off or flashing rapidly.
Control Board Communication Failure
E11
Furnace shows E11; burners light but shut off within a few seconds, repeating several times.
Flame Sense Loss During Run
E12
Furnace displays E12; inducer and blower may run but burners do not ignite.
Ignition Lockout (Too Many Failed Attempts)
E13
Furnace shows E13; blower runs but no heat, often after a long run cycle.
Auxiliary Limit or Vent Temperature Switch Open
E14
Furnace displays E14; blower does not start or starts late, causing short cycling.
Blower Motor Failure / Blower Not Proving
E15
Furnace shows E15; unit shuts down and may display overvoltage/undervoltage warning.
Line Voltage Out of Range
E16
Furnace displays E16; condensate pump runs frequently or furnace shuts down during wet weather.
Condensate Drain Blocked / Float Switch Open
E17
Furnace shows E17; unit may run at reduced capacity or shut down intermittently.
Supply Air Temperature Sensor Fault
E18
Furnace displays E18; two-stage or modulating models may be stuck in low fire or fail to change stages.
Gas Valve Modulation / Stage Control Fault
E19
Furnace shows E19; integrated humidifier or accessory control not functioning.
Accessory Output Fault (Humidifier/Dehumidifier)
E20
Furnace displays E20; unit may shut down on very cold days or after long run times.
Flue Gas Temperature Too High
Symptom
Furnace blower runs continuously even when thermostat is not calling for heat or fan.
Blower Stuck in Fan-On / Limit Mode
Symptom
Furnace causes a strong chemical or metallic odor when running.
Contaminated Combustion Air / Overheated Components
Symptom
Furnace cycles on and off rapidly (every 1–5 minutes) without reaching set temperature.
Thermostat or Control Short Cycling
Symptom
Furnace emits a burning smell when it starts, especially at the beginning of the heating season.
Dust Burn-Off / Overheating Components
Symptom
Furnace ignites but flame appears yellow and lazy instead of blue and stable.
Improper Combustion / Insufficient Air
Symptom
Furnace is very loud at the return grille, with a whistling or roaring sound.
Return Air Restriction / High Static Pressure
Symptom
Furnace makes loud banging or booming noise at startup.
Delayed Ignition / Burner Flashback
Symptom
Furnace occasionally trips the household circuit breaker during startup.
Overcurrent on Furnace Circuit
Symptom
Furnace produces a high-pitched whine or screeching noise during operation.
Blower or Inducer Bearing Wear
Symptom
Furnace runs but produces no heat; blower runs continuously with room air only.
Burners Not Igniting (No Heat, No Error Code)
Symptom
Furnace runs but some rooms are too cold while others are too warm.
Airflow Imbalance / Duct Issues
Symptom
Furnace short cycles: starts, runs for a few minutes, then shuts off and restarts frequently.
Overheating / Limit Cycling
Symptom
Furnace starts then shuts off after a few seconds; thermostat display goes blank or resets.
Low Voltage Short / Transformer Overload
Symptom
Furnace vibrates excessively and causes rattling in ductwork when running.
Blower Imbalance / Loose Mounting
Symptom
Furnace will not start at all; no blower, no inducer, no lights on control board.
No Power to Furnace
Symptom
Rust-colored water or corrosion visible inside furnace cabinet or on burners.
Condensation / Corrosion in Heat Exchanger Area
Symptom
Water leaking around the base of the furnace during heating operation.
Condensate Leak from High-Efficiency Furnace
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| E01 |
Furnace will not start; control board displays E01 immediately after a call for heat.
|
No Flame Detected on Ignition | View Details |
| E02 |
Furnace attempts to start but shuts down before ignition; E02 displayed on Alpha control module.
|
Ignition Failure / Igniter Fault | View Details |
| E03 |
Furnace starts, inducer runs, but burners do not light; E03 code appears after several attempts.
|
Gas Valve Not Energizing | View Details |
| E04 |
Furnace displays E04 and will not start; inducer motor does not run.
|
Inducer Motor Failure / Pressure Switch Not Proving | View Details |
| E05 |
Furnace starts but shuts down shortly after ignition; E05 displayed, blower may continue to run.
|
High Limit Switch Open (Overheat Condition) | View Details |
| E06 |
Furnace displays E06 and will not fire; inducer may start briefly then stop.
|
Pressure Switch Stuck Open | View Details |
| E07 |
Furnace shows E07; inducer runs continuously without ignition sequence starting.
|
Pressure Switch Stuck Closed | View Details |
| E08 |
Furnace displays E08; blower runs but burners do not light, or furnace shuts down mid-cycle.
|
Rollout Switch Open (Flame Rollout Detected) | View Details |
| E09 |
Furnace shows E09; blower may run continuously and burners will not ignite.
|
Low Temperature Limit / Freeze Protection Trip | View Details |
| E10 |
Furnace displays E10; no response to thermostat calls, control board LEDs may be off or flashing rapidly.
|
Control Board Communication Failure | View Details |
| E11 |
Furnace shows E11; burners light but shut off within a few seconds, repeating several times.
|
Flame Sense Loss During Run | View Details |
| E12 |
Furnace displays E12; inducer and blower may run but burners do not ignite.
|
Ignition Lockout (Too Many Failed Attempts) | View Details |
| E13 |
Furnace shows E13; blower runs but no heat, often after a long run cycle.
|
Auxiliary Limit or Vent Temperature Switch Open | View Details |
| E14 |
Furnace displays E14; blower does not start or starts late, causing short cycling.
|
Blower Motor Failure / Blower Not Proving | View Details |
| E15 |
Furnace shows E15; unit shuts down and may display overvoltage/undervoltage warning.
|
Line Voltage Out of Range | View Details |
| E16 |
Furnace displays E16; condensate pump runs frequently or furnace shuts down during wet weather.
|
Condensate Drain Blocked / Float Switch Open | View Details |
| E17 |
Furnace shows E17; unit may run at reduced capacity or shut down intermittently.
|
Supply Air Temperature Sensor Fault | View Details |
| E18 |
Furnace displays E18; two-stage or modulating models may be stuck in low fire or fail to change stages.
|
Gas Valve Modulation / Stage Control Fault | View Details |
| E19 |
Furnace shows E19; integrated humidifier or accessory control not functioning.
|
Accessory Output Fault (Humidifier/Dehumidifier) | View Details |
| E20 |
Furnace displays E20; unit may shut down on very cold days or after long run times.
|
Flue Gas Temperature Too High | View Details |
| – |
Furnace blower runs continuously even when thermostat is not calling for heat or fan.
|
Blower Stuck in Fan-On / Limit Mode | View Details |
| – |
Furnace causes a strong chemical or metallic odor when running.
|
Contaminated Combustion Air / Overheated Components | View Details |
| – |
Furnace cycles on and off rapidly (every 1–5 minutes) without reaching set temperature.
|
Thermostat or Control Short Cycling | View Details |
| – |
Furnace emits a burning smell when it starts, especially at the beginning of the heating season.
|
Dust Burn-Off / Overheating Components | View Details |
| – |
Furnace ignites but flame appears yellow and lazy instead of blue and stable.
|
Improper Combustion / Insufficient Air | View Details |
| – |
Furnace is very loud at the return grille, with a whistling or roaring sound.
|
Return Air Restriction / High Static Pressure | View Details |
| – |
Furnace makes loud banging or booming noise at startup.
|
Delayed Ignition / Burner Flashback | View Details |
| – |
Furnace occasionally trips the household circuit breaker during startup.
|
Overcurrent on Furnace Circuit | View Details |
| – |
Furnace produces a high-pitched whine or screeching noise during operation.
|
Blower or Inducer Bearing Wear | View Details |
| – |
Furnace runs but produces no heat; blower runs continuously with room air only.
|
Burners Not Igniting (No Heat, No Error Code) | View Details |
| – |
Furnace runs but some rooms are too cold while others are too warm.
|
Airflow Imbalance / Duct Issues | View Details |
| – |
Furnace short cycles: starts, runs for a few minutes, then shuts off and restarts frequently.
|
Overheating / Limit Cycling | View Details |
| – |
Furnace starts then shuts off after a few seconds; thermostat display goes blank or resets.
|
Low Voltage Short / Transformer Overload | View Details |
| – |
Furnace vibrates excessively and causes rattling in ductwork when running.
|
Blower Imbalance / Loose Mounting | View Details |
| – |
Furnace will not start at all; no blower, no inducer, no lights on control board.
|
No Power to Furnace | View Details |
| – |
Rust-colored water or corrosion visible inside furnace cabinet or on burners.
|
Condensation / Corrosion in Heat Exchanger Area | View Details |
| – |
Water leaking around the base of the furnace during heating operation.
|
Condensate Leak from High-Efficiency Furnace | View Details |
No matching codes found
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