Biasi
Biasi Boilers Error Codes
Complete list of fault codes and troubleshooting guides. Use the search below to find your specific error.
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01
Boiler locks out with code 01, burner does not ignite, red lockout light on control panel.
Ignition Failure / Flame Not Detected
02
Boiler displays error 02 and shuts down shortly after starting, burner stops unexpectedly.
Flame Loss During Operation
03
Boiler shows error 03, fan does not start or stops quickly, no ignition attempt.
Fan / Air Pressure Switch Fault
04
Boiler displays error 04 and will not start, often accompanied by overheat light or very hot casing.
Primary Overheat Thermostat Tripped
05
Boiler shows error 05, no heating or hot water, fan may run but no ignition sequence completes.
Air Pressure Switch Not Proving
06
Boiler displays error 06, temperature reading is erratic or boiler overheats quickly then shuts down.
Flow NTC Sensor Fault
07
Boiler shows error 07, hot water temperature unstable or boiler cycles rapidly on DHW demand.
DHW NTC Sensor Fault
08
Boiler displays error 08, no heating, pump may run continuously, temperature display may be fixed at a low or high value.
Return NTC Sensor Fault
09
Boiler shows error 09, will not fire, may indicate low system pressure or water shortage.
Low Water Pressure / Water Pressure Switch Fault
10
Boiler displays error 10, often associated with rapid temperature rise and shutdown.
Primary Circuit Overtemperature / Flow Blockage
11
Boiler shows error 11, no response to thermostat, display may be normal but no heating demand is recognised.
Room Thermostat / External Control Fault
12
Boiler displays error 12, fan runs but ignition does not occur, may indicate gas valve or flame sensing issue.
Gas Valve / Flame Control Fault
13
Boiler shows error 13, display may indicate flue or fan fault, boiler will not ignite.
Flue System / Fan Speed Fault
14
Boiler displays error 14, often associated with very low or very high mains voltage conditions.
Mains Supply / PCB Power Fault
15
Boiler shows error 15, may indicate communication error between display and main PCB or internal electronics fault.
PCB Communication / Internal Fault
16
Boiler displays error 16, often related to domestic hot water flow detection problems.
DHW Flow Sensor / Turbine Fault
17
Boiler shows error 17, may indicate diverter valve position error or failure to switch between heating and hot water.
Diverter Valve Position Fault
18
Boiler displays error 18, often associated with condensate or flue gas recirculation issues.
Condensate / Flue Blockage Fault
19
Boiler shows error 19, may indicate expansion vessel or pressure-related fault during heating.
Expansion Vessel / Pressure Rise Fault
Symptom
Boiler display works but no response to hot water or heating demand, no fan or ignition sequence starts.
No Demand Recognition
Symptom
Boiler does not start at all, no lights or display, appears completely dead.
No Power / Dead Boiler
Symptom
Boiler emits a strong smell of gas or combustion fumes around the casing or flue area.
Gas Leak / Flue Gas Escape
Symptom
Boiler frequently locks out and requires manual reset, with varying or no error codes.
Intermittent Lockout
Symptom
Boiler frequently loses pressure, requiring regular top-ups via the filling loop.
Chronic Pressure Loss
Symptom
Boiler frequently short cycles on central heating, turning on and off every few minutes, rooms never reach set temperature comfortably.
Short Cycling on Central Heating
Symptom
Boiler frequently trips the household RCD or MCB when attempting to start.
Electrical Short / Earth Leakage
Symptom
Boiler is very noisy, with whistling, droning, or vibrating sounds during operation.
Excessive Operational Noise / Vibration
Symptom
Boiler leaking water from underneath the casing or from pipe connections, no specific error code displayed.
Internal Water Leak
Symptom
Boiler makes loud banging or knocking noises (kettling) during operation, especially on heating demand.
Kettling / Localised Boiling in Heat Exchanger
Symptom
Boiler produces hot water but central heating does not come on, even though controls are calling for heat.
No Central Heating Output
Symptom
Boiler runs but radiators remain cold or only lukewarm, hot water may still work.
Poor Central Heating Circulation
Symptom
Boiler runs for central heating but does not produce any domestic hot water, or hot water is only lukewarm.
No / Insufficient Domestic Hot Water
Symptom
Boiler starts then shuts down after a few seconds, with no specific error code, radiators and hot water remain cold.
Short Cycling on Start-up
Symptom
Boiler's condensate pipe repeatedly freezes in cold weather, causing lockouts or shutdowns.
Frozen Condensate Pipe
Symptom
Hot water temperature fluctuates between hot and cold during use, especially at low flow rates.
Unstable DHW Temperature
Symptom
Radiators get hot when only hot water is being used, even though heating is turned off.
Diverter Valve Passing to Heating Circuit
| Error Code | Symptom | Fault Type | Guide |
|---|---|---|---|
| 01 |
Boiler locks out with code 01, burner does not ignite, red lockout light on control panel.
|
Ignition Failure / Flame Not Detected | View Details |
| 02 |
Boiler displays error 02 and shuts down shortly after starting, burner stops unexpectedly.
|
Flame Loss During Operation | View Details |
| 03 |
Boiler shows error 03, fan does not start or stops quickly, no ignition attempt.
|
Fan / Air Pressure Switch Fault | View Details |
| 04 |
Boiler displays error 04 and will not start, often accompanied by overheat light or very hot casing.
|
Primary Overheat Thermostat Tripped | View Details |
| 05 |
Boiler shows error 05, no heating or hot water, fan may run but no ignition sequence completes.
|
Air Pressure Switch Not Proving | View Details |
| 06 |
Boiler displays error 06, temperature reading is erratic or boiler overheats quickly then shuts down.
|
Flow NTC Sensor Fault | View Details |
| 07 |
Boiler shows error 07, hot water temperature unstable or boiler cycles rapidly on DHW demand.
|
DHW NTC Sensor Fault | View Details |
| 08 |
Boiler displays error 08, no heating, pump may run continuously, temperature display may be fixed at a low or high value.
|
Return NTC Sensor Fault | View Details |
| 09 |
Boiler shows error 09, will not fire, may indicate low system pressure or water shortage.
|
Low Water Pressure / Water Pressure Switch Fault | View Details |
| 10 |
Boiler displays error 10, often associated with rapid temperature rise and shutdown.
|
Primary Circuit Overtemperature / Flow Blockage | View Details |
| 11 |
Boiler shows error 11, no response to thermostat, display may be normal but no heating demand is recognised.
|
Room Thermostat / External Control Fault | View Details |
| 12 |
Boiler displays error 12, fan runs but ignition does not occur, may indicate gas valve or flame sensing issue.
|
Gas Valve / Flame Control Fault | View Details |
| 13 |
Boiler shows error 13, display may indicate flue or fan fault, boiler will not ignite.
|
Flue System / Fan Speed Fault | View Details |
| 14 |
Boiler displays error 14, often associated with very low or very high mains voltage conditions.
|
Mains Supply / PCB Power Fault | View Details |
| 15 |
Boiler shows error 15, may indicate communication error between display and main PCB or internal electronics fault.
|
PCB Communication / Internal Fault | View Details |
| 16 |
Boiler displays error 16, often related to domestic hot water flow detection problems.
|
DHW Flow Sensor / Turbine Fault | View Details |
| 17 |
Boiler shows error 17, may indicate diverter valve position error or failure to switch between heating and hot water.
|
Diverter Valve Position Fault | View Details |
| 18 |
Boiler displays error 18, often associated with condensate or flue gas recirculation issues.
|
Condensate / Flue Blockage Fault | View Details |
| 19 |
Boiler shows error 19, may indicate expansion vessel or pressure-related fault during heating.
|
Expansion Vessel / Pressure Rise Fault | View Details |
| – |
Boiler display works but no response to hot water or heating demand, no fan or ignition sequence starts.
|
No Demand Recognition | View Details |
| – |
Boiler does not start at all, no lights or display, appears completely dead.
|
No Power / Dead Boiler | View Details |
| – |
Boiler emits a strong smell of gas or combustion fumes around the casing or flue area.
|
Gas Leak / Flue Gas Escape | View Details |
| – |
Boiler frequently locks out and requires manual reset, with varying or no error codes.
|
Intermittent Lockout | View Details |
| – |
Boiler frequently loses pressure, requiring regular top-ups via the filling loop.
|
Chronic Pressure Loss | View Details |
| – |
Boiler frequently short cycles on central heating, turning on and off every few minutes, rooms never reach set temperature comfortably.
|
Short Cycling on Central Heating | View Details |
| – |
Boiler frequently trips the household RCD or MCB when attempting to start.
|
Electrical Short / Earth Leakage | View Details |
| – |
Boiler is very noisy, with whistling, droning, or vibrating sounds during operation.
|
Excessive Operational Noise / Vibration | View Details |
| – |
Boiler leaking water from underneath the casing or from pipe connections, no specific error code displayed.
|
Internal Water Leak | View Details |
| – |
Boiler makes loud banging or knocking noises (kettling) during operation, especially on heating demand.
|
Kettling / Localised Boiling in Heat Exchanger | View Details |
| – |
Boiler produces hot water but central heating does not come on, even though controls are calling for heat.
|
No Central Heating Output | View Details |
| – |
Boiler runs but radiators remain cold or only lukewarm, hot water may still work.
|
Poor Central Heating Circulation | View Details |
| – |
Boiler runs for central heating but does not produce any domestic hot water, or hot water is only lukewarm.
|
No / Insufficient Domestic Hot Water | View Details |
| – |
Boiler starts then shuts down after a few seconds, with no specific error code, radiators and hot water remain cold.
|
Short Cycling on Start-up | View Details |
| – |
Boiler's condensate pipe repeatedly freezes in cold weather, causing lockouts or shutdowns.
|
Frozen Condensate Pipe | View Details |
| – |
Hot water temperature fluctuates between hot and cold during use, especially at low flow rates.
|
Unstable DHW Temperature | View Details |
| – |
Radiators get hot when only hot water is being used, even though heating is turned off.
|
Diverter Valve Passing to Heating Circuit | View Details |
No matching codes found
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