Wolf Boilers Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
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A01
Boiler does not ignite, display shows A01 lockout, red fault LED lit
Ignition Failure / No Flame Detection
A02
Boiler locks out with A02, burner starts then shuts down after a few seconds
Flame Loss During Operation
A03
Boiler shows A03 and shuts down, overheat symbol may be displayed
Safety Temperature Limiter (STB) Tripped / Overheat
A04
Display shows A04, boiler does not start, low pressure symbol may be lit
Low System Water Pressure
A05
Boiler shows A05, fan runs but burner does not ignite or shuts down quickly
Flue Gas / Air Pressure Fault
A06
Boiler displays A06, no heating or hot water, fan may not start
Fan Fault / No Airflow Detected
A07
Boiler shows A07, heating stops, flow temperature rises rapidly
Insufficient Circulation / Flow Temperature Rise Too Fast
A08
Boiler displays A08, burner does not start, domestic hot water and heating unavailable
Flow Temperature Sensor Fault (NTC Open/Short)
A09
Boiler shows A09, hot water temperature unstable or boiler shuts down intermittently
Return Temperature Sensor Fault (NTC Open/Short)
A10
Boiler displays A10, domestic hot water (DHW) not available or temperature incorrect
DHW Temperature Sensor Fault
A11
Boiler shows A11, burner does not start, control panel unresponsive to heat demand
Communication Fault Between Boiler PCB and Controller
A12
Boiler displays A12, burner output limited, heating slow to reach set temperature
Modulation / Gas Valve Control Fault
A13
Boiler shows A13, burner shuts down, flue gas temperature too high
Flue Gas Temperature Limit Exceeded
A14
Boiler displays A14, no ignition, fan may run briefly then stop
Air Pressure Switch Not Proving / Stuck
A15
Boiler shows A15, burner stops, condensate may be visible around boiler
Condensate Drain Blocked / Backflow Detected
A16
Boiler displays A16, burner output limited, system may be noisy
Flow Sensor / Flow Switch Fault (Low or No Flow Detection)
A17
Boiler shows A17, burner stops, error appears after long run time
Return Temperature Too High / Delta-T Too Low
A18
Boiler displays A18, no response to room thermostat, heating remains off
External Control / Thermostat Input Fault
A19
Boiler shows A19, display may flicker, random lockouts
Mains Voltage / Power Supply Fault
A20
Boiler displays A20, burner does not start, safety chain open
Safety Circuit Open (Limit Switch / Safety Chain Fault)
Symptom
Boiler display works but does not respond to room thermostat changes, heating stays on or off permanently
Control / Thermostat Communication Issue
Symptom
Boiler flue terminal dripping water or staining the wall
Condensate / Flue Drainage Issue
Symptom
Boiler frequently locks out during very cold weather, condensate pipe outside is icy
Frozen Condensate Pipe
Symptom
Boiler frequently loses pressure and needs topping up every few days
Chronic Pressure Loss
Symptom
Boiler leaking water from underneath the casing
Internal Water Leak
Symptom
Boiler makes loud banging or knocking noises (kettling) during operation
Heat Exchanger Kettling / Localised Boiling
Symptom
Boiler pressure rises rapidly when heating and may discharge water from safety valve
Over-Pressurisation Under Load
Symptom
Boiler room feels unusually hot, boiler casing very warm even when not firing
Standby Overheating / Residual Heat Issue
Symptom
Boiler runs but radiators remain cold or only lukewarm
Poor Heating Performance / No Circulation
Symptom
Boiler starts then shuts down after a few seconds without showing a specific error code
Short Cycling / Unstable Combustion
Symptom
Boiler vibrates excessively and transmits noise through the building structure
Mechanical Vibration / Mounting Fault
Symptom
Boiler will not start at all, no display or lights
No Power / Dead Boiler
Symptom
Domestic hot water temperature fluctuates between hot and cold
Unstable DHW Temperature Control
Symptom
No domestic hot water, but heating works normally
DHW Priority / Diverter Fault
Symptom
Radiators get hot even when there is no call for heating
Unwanted Heating / Valve Bypass
Symptom
Smell of burning or melted plastic from the boiler casing
Overheating Electrical Component
Symptom
Strong smell of gas near the boiler
Gas Leak in Boiler or Nearby Pipework
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| A01 |
Boiler does not ignite, display shows A01 lockout, red fault LED lit
|
Ignition Failure / No Flame Detection | View Details |
| A02 |
Boiler locks out with A02, burner starts then shuts down after a few seconds
|
Flame Loss During Operation | View Details |
| A03 |
Boiler shows A03 and shuts down, overheat symbol may be displayed
|
Safety Temperature Limiter (STB) Tripped / Overheat | View Details |
| A04 |
Display shows A04, boiler does not start, low pressure symbol may be lit
|
Low System Water Pressure | View Details |
| A05 |
Boiler shows A05, fan runs but burner does not ignite or shuts down quickly
|
Flue Gas / Air Pressure Fault | View Details |
| A06 |
Boiler displays A06, no heating or hot water, fan may not start
|
Fan Fault / No Airflow Detected | View Details |
| A07 |
Boiler shows A07, heating stops, flow temperature rises rapidly
|
Insufficient Circulation / Flow Temperature Rise Too Fast | View Details |
| A08 |
Boiler displays A08, burner does not start, domestic hot water and heating unavailable
|
Flow Temperature Sensor Fault (NTC Open/Short) | View Details |
| A09 |
Boiler shows A09, hot water temperature unstable or boiler shuts down intermittently
|
Return Temperature Sensor Fault (NTC Open/Short) | View Details |
| A10 |
Boiler displays A10, domestic hot water (DHW) not available or temperature incorrect
|
DHW Temperature Sensor Fault | View Details |
| A11 |
Boiler shows A11, burner does not start, control panel unresponsive to heat demand
|
Communication Fault Between Boiler PCB and Controller | View Details |
| A12 |
Boiler displays A12, burner output limited, heating slow to reach set temperature
|
Modulation / Gas Valve Control Fault | View Details |
| A13 |
Boiler shows A13, burner shuts down, flue gas temperature too high
|
Flue Gas Temperature Limit Exceeded | View Details |
| A14 |
Boiler displays A14, no ignition, fan may run briefly then stop
|
Air Pressure Switch Not Proving / Stuck | View Details |
| A15 |
Boiler shows A15, burner stops, condensate may be visible around boiler
|
Condensate Drain Blocked / Backflow Detected | View Details |
| A16 |
Boiler displays A16, burner output limited, system may be noisy
|
Flow Sensor / Flow Switch Fault (Low or No Flow Detection) | View Details |
| A17 |
Boiler shows A17, burner stops, error appears after long run time
|
Return Temperature Too High / Delta-T Too Low | View Details |
| A18 |
Boiler displays A18, no response to room thermostat, heating remains off
|
External Control / Thermostat Input Fault | View Details |
| A19 |
Boiler shows A19, display may flicker, random lockouts
|
Mains Voltage / Power Supply Fault | View Details |
| A20 |
Boiler displays A20, burner does not start, safety chain open
|
Safety Circuit Open (Limit Switch / Safety Chain Fault) | View Details |
| – |
Boiler display works but does not respond to room thermostat changes, heating stays on or off permanently
|
Control / Thermostat Communication Issue | View Details |
| – |
Boiler flue terminal dripping water or staining the wall
|
Condensate / Flue Drainage Issue | View Details |
| – |
Boiler frequently locks out during very cold weather, condensate pipe outside is icy
|
Frozen Condensate Pipe | View Details |
| – |
Boiler frequently loses pressure and needs topping up every few days
|
Chronic Pressure Loss | View Details |
| – |
Boiler leaking water from underneath the casing
|
Internal Water Leak | View Details |
| – |
Boiler makes loud banging or knocking noises (kettling) during operation
|
Heat Exchanger Kettling / Localised Boiling | View Details |
| – |
Boiler pressure rises rapidly when heating and may discharge water from safety valve
|
Over-Pressurisation Under Load | View Details |
| – |
Boiler room feels unusually hot, boiler casing very warm even when not firing
|
Standby Overheating / Residual Heat Issue | View Details |
| – |
Boiler runs but radiators remain cold or only lukewarm
|
Poor Heating Performance / No Circulation | View Details |
| – |
Boiler starts then shuts down after a few seconds without showing a specific error code
|
Short Cycling / Unstable Combustion | View Details |
| – |
Boiler vibrates excessively and transmits noise through the building structure
|
Mechanical Vibration / Mounting Fault | View Details |
| – |
Boiler will not start at all, no display or lights
|
No Power / Dead Boiler | View Details |
| – |
Domestic hot water temperature fluctuates between hot and cold
|
Unstable DHW Temperature Control | View Details |
| – |
No domestic hot water, but heating works normally
|
DHW Priority / Diverter Fault | View Details |
| – |
Radiators get hot even when there is no call for heating
|
Unwanted Heating / Valve Bypass | View Details |
| – |
Smell of burning or melted plastic from the boiler casing
|
Overheating Electrical Component | View Details |
| – |
Strong smell of gas near the boiler
|
Gas Leak in Boiler or Nearby Pipework | View Details |
No matching codes found
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