Nibe
Nibe Furnaces Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
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A1
Furnace/heat pump stops and displays A1 alarm, no heating or hot water
High‑pressure switch tripped
A2
Unit shows A2 alarm, compressor will not start, no heating or cooling
Low‑pressure switch tripped
A3
Display shows A3, unit locked out, compressor stopped
High discharge gas temperature
A4
A4 alarm, unit stops, no heating output
Brine/ground loop low temperature alarm (for ground‑source Nibe furnaces)
A5
A5 alarm, electric backup heater disabled, reduced heating capacity
Electric immersion heater overheat / high‑limit trip
A6
A6 alarm, compressor locked out, unit may run only on electric backup
Compressor overload / motor protection trip
A7
A7 alarm, no domestic hot water production
Hot water temperature sensor fault
A8
A8 alarm, outdoor temperature reading missing or unrealistic, system may run incorrectly
Outdoor temperature sensor fault
A9
A9 alarm, flow temperature reading incorrect, unit cycles or shuts down
Heating flow temperature sensor fault
B1
B1 alarm, no circulation in heating system, radiators cold
Heating circulation pump fault
B2
B2 alarm, brine/ground loop pump not running, A4 alarms may also appear
Brine circulation pump fault
B3
B3 alarm, no hot water circulation through cylinder coil, poor hot water performance
Hot water circulation pump fault
B4
B4 alarm, fan not running, no airflow through furnace/air module
Supply fan fault
B5
B5 alarm, reversing valve not operating, no change between heating and cooling (for reversible Nibe units)
Reversing valve fault
C1
C1 alarm, communication error between display unit and main control board
Internal communication bus fault
C2
C2 alarm, communication error with external accessory (e.g., Nibe SMO, ECS, or pool module)
Accessory communication fault
C3
C3 alarm, internal sensor bus error, multiple sensor readings missing
Internal sensor communication fault
D1
D1 alarm, high temperature in furnace cabinet, unit shuts down
Cabinet overtemperature
D2
D2 alarm, flow temperature too high, safety thermostat may trip
Overtemperature in heating circuit
D3
D3 alarm, low system water pressure, unit stops to protect system
Low water pressure in heating circuit
D4
D4 alarm, high system water pressure, safety valve may discharge water
High water pressure in heating circuit
E1
E1 alarm, electric heater stage 1 fault, reduced heating capacity
Electric heater element failure (stage 1)
E2
E2 alarm, electric heater stage 2 fault, backup heating limited
Electric heater element failure (stage 2)
E3
E3 alarm, 3‑way valve not reaching correct position, incorrect distribution between heating and hot water
3‑way diverter valve fault
E4
E4 alarm, defrost function fault on air‑source Nibe furnace/heat pump
Defrost cycle malfunction
E5
E5 alarm, flue gas temperature too high (for Nibe furnaces with combustion module), burner shuts down
Flue gas overtemperature
E6
E6 alarm, flame failure or no flame detected (combustion module), burner locks out
Flame detection / ignition fault
E7
E7 alarm, condensate level high or condensate pump fault, unit may shut down
Condensate drainage fault
Symptom
Clicking noises from Nibe furnace but no start of compressor or heater
Contactor chatter / failed start
Symptom
Furnace does not start at all, display blank or unresponsive
No power / main control failure
Symptom
Furnace frequently starts and stops (short cycling), room temperature unstable
Short cycling / poor control tuning
Symptom
Furnace runs but radiators or underfloor heating remain lukewarm or cold
Insufficient heating output / undersized or misconfigured system
Symptom
Gurgling or rushing water sounds in radiators or inside Nibe unit
Air in heating system
Symptom
Loud humming or vibration from Nibe furnace during operation
Mechanical vibration / mounting fault
Symptom
Nibe furnace display shows normal operation but room remains too cold
Underheating / control undershoot
Symptom
Nibe furnace display shows normal operation but room remains too hot
Overheating / control overshoot
Symptom
No domestic hot water or very limited hot water, but heating works normally
DHW production fault without alarm
Symptom
Outdoor Nibe unit (for air‑source furnace/heat pump) covered in ice, poor heating performance
Excessive icing / defrost inefficiency
Symptom
Unpleasant smell (burning or plastic) from Nibe furnace cabinet
Overheating electrical component or dust burn‑off
Symptom
Visible water leak from inside the Nibe furnace cabinet
Internal water leak
Symptom
Water leaking from safety valve near Nibe furnace or hot water cylinder
Safety valve discharge
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| A1 |
Furnace/heat pump stops and displays A1 alarm, no heating or hot water
|
High‑pressure switch tripped | View Details |
| A2 |
Unit shows A2 alarm, compressor will not start, no heating or cooling
|
Low‑pressure switch tripped | View Details |
| A3 |
Display shows A3, unit locked out, compressor stopped
|
High discharge gas temperature | View Details |
| A4 |
A4 alarm, unit stops, no heating output
|
Brine/ground loop low temperature alarm (for ground‑source Nibe furnaces) | View Details |
| A5 |
A5 alarm, electric backup heater disabled, reduced heating capacity
|
Electric immersion heater overheat / high‑limit trip | View Details |
| A6 |
A6 alarm, compressor locked out, unit may run only on electric backup
|
Compressor overload / motor protection trip | View Details |
| A7 |
A7 alarm, no domestic hot water production
|
Hot water temperature sensor fault | View Details |
| A8 |
A8 alarm, outdoor temperature reading missing or unrealistic, system may run incorrectly
|
Outdoor temperature sensor fault | View Details |
| A9 |
A9 alarm, flow temperature reading incorrect, unit cycles or shuts down
|
Heating flow temperature sensor fault | View Details |
| B1 |
B1 alarm, no circulation in heating system, radiators cold
|
Heating circulation pump fault | View Details |
| B2 |
B2 alarm, brine/ground loop pump not running, A4 alarms may also appear
|
Brine circulation pump fault | View Details |
| B3 |
B3 alarm, no hot water circulation through cylinder coil, poor hot water performance
|
Hot water circulation pump fault | View Details |
| B4 |
B4 alarm, fan not running, no airflow through furnace/air module
|
Supply fan fault | View Details |
| B5 |
B5 alarm, reversing valve not operating, no change between heating and cooling (for reversible Nibe units)
|
Reversing valve fault | View Details |
| C1 |
C1 alarm, communication error between display unit and main control board
|
Internal communication bus fault | View Details |
| C2 |
C2 alarm, communication error with external accessory (e.g., Nibe SMO, ECS, or pool module)
|
Accessory communication fault | View Details |
| C3 |
C3 alarm, internal sensor bus error, multiple sensor readings missing
|
Internal sensor communication fault | View Details |
| D1 |
D1 alarm, high temperature in furnace cabinet, unit shuts down
|
Cabinet overtemperature | View Details |
| D2 |
D2 alarm, flow temperature too high, safety thermostat may trip
|
Overtemperature in heating circuit | View Details |
| D3 |
D3 alarm, low system water pressure, unit stops to protect system
|
Low water pressure in heating circuit | View Details |
| D4 |
D4 alarm, high system water pressure, safety valve may discharge water
|
High water pressure in heating circuit | View Details |
| E1 |
E1 alarm, electric heater stage 1 fault, reduced heating capacity
|
Electric heater element failure (stage 1) | View Details |
| E2 |
E2 alarm, electric heater stage 2 fault, backup heating limited
|
Electric heater element failure (stage 2) | View Details |
| E3 |
E3 alarm, 3‑way valve not reaching correct position, incorrect distribution between heating and hot water
|
3‑way diverter valve fault | View Details |
| E4 |
E4 alarm, defrost function fault on air‑source Nibe furnace/heat pump
|
Defrost cycle malfunction | View Details |
| E5 |
E5 alarm, flue gas temperature too high (for Nibe furnaces with combustion module), burner shuts down
|
Flue gas overtemperature | View Details |
| E6 |
E6 alarm, flame failure or no flame detected (combustion module), burner locks out
|
Flame detection / ignition fault | View Details |
| E7 |
E7 alarm, condensate level high or condensate pump fault, unit may shut down
|
Condensate drainage fault | View Details |
| – |
Clicking noises from Nibe furnace but no start of compressor or heater
|
Contactor chatter / failed start | View Details |
| – |
Furnace does not start at all, display blank or unresponsive
|
No power / main control failure | View Details |
| – |
Furnace frequently starts and stops (short cycling), room temperature unstable
|
Short cycling / poor control tuning | View Details |
| – |
Furnace runs but radiators or underfloor heating remain lukewarm or cold
|
Insufficient heating output / undersized or misconfigured system | View Details |
| – |
Gurgling or rushing water sounds in radiators or inside Nibe unit
|
Air in heating system | View Details |
| – |
Loud humming or vibration from Nibe furnace during operation
|
Mechanical vibration / mounting fault | View Details |
| – |
Nibe furnace display shows normal operation but room remains too cold
|
Underheating / control undershoot | View Details |
| – |
Nibe furnace display shows normal operation but room remains too hot
|
Overheating / control overshoot | View Details |
| – |
No domestic hot water or very limited hot water, but heating works normally
|
DHW production fault without alarm | View Details |
| – |
Outdoor Nibe unit (for air‑source furnace/heat pump) covered in ice, poor heating performance
|
Excessive icing / defrost inefficiency | View Details |
| – |
Unpleasant smell (burning or plastic) from Nibe furnace cabinet
|
Overheating electrical component or dust burn‑off | View Details |
| – |
Visible water leak from inside the Nibe furnace cabinet
|
Internal water leak | View Details |
| – |
Water leaking from safety valve near Nibe furnace or hot water cylinder
|
Safety valve discharge | View Details |
No matching codes found
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