Check gap between ionisation electrode and burner gauze assembly. Check flue system. Remove flue gas recirculation if required. Reset device.
Viessmann Vitodens 200-W B2HF System Fault codes & diagnostics
133 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
The fault code is already on your display
Note it down before pressing reset — resetting clears the code immediately. How to read fault codes →
Severity at a glance
Each cell = one fault code. Hover to identify.All 133 documented codes
Tap any card for details
A.11 Your boiler has stopped working because the water pressure inside your heating system is too low.
Your boiler has stopped working because the water pressure inside your heating system is too low.
What to check first
- Locate the external filling loop, which is a flexible silver hose connected to two valves under your boiler.
- Open the valves slowly to allow mains water into the system until the pressure gauge reads between 1.0 and 1.5 bar.
- Close both valves tightly and check the display to see if the error has cleared.
Parts commonly replaced
- Filling loop
- Pressure relief valve
- Expansion vessel
Related codes
A.12 Your boiler's internal clock has lost its memory because a small backup battery has run out of power.
Your boiler's internal clock has lost its memory because a small backup battery has run out of power.
What to check first
- Locate the control panel (HMU) on the front of the boiler
- Identify the small circular battery slot containing the CR2032 coin cell
- Carefully swap the old battery for a new CR2032 battery and reset the time and date
Parts commonly replaced
- CR2032 Lithium Battery
Related codes
A.18 Your boiler has detected that waste water is backing up inside the main heating unit, which is preventing it from running safely.
Your boiler has detected that waste water is backing up inside the main heating unit, which is preventing it from running safely.
Parts commonly replaced
- Condensate trap
- Condensate discharge pipe
- Electrode block
Related codes
A.20 Your boiler is simply notifying you that it was unable to set a reminder for its next scheduled service.
Your boiler is simply notifying you that it was unable to set a reminder for its next scheduled service.
What to check first
- Navigate to the main menu on the control panel
- Go to 'Settings' and then 'Service'
- Attempt to manually reset the service interval or acknowledge the notification
Related codes
A.21 Your central heating system currently has too much water inside it, causing the internal pressure to rise above the safe limit.
Your central heating system currently has too much water inside it, causing the internal pressure to rise above the safe limit.
What to check first
- Locate a radiator in your home, preferably upstairs.
- Place a cloth and a container underneath the radiator bleed valve.
- Use a radiator key to open the valve slightly and release water until the pressure gauge on the boiler drops to between 1.0 and 1.5 bar.
Parts commonly replaced
- Pressure relief valve
- Expansion vessel
- Pressure sensor
Related codes
F.5 Your boiler has stopped working because it cannot correctly measure the temperature of the water leaving the unit due to a sensor or wiring fault.
Your boiler has stopped working because it cannot correctly measure the temperature of the water leaving the unit due to a sensor or wiring fault.
Parts commonly replaced
- Flow temperature sensor (NTC)
- Wiring harness
- Control PCB
Related codes
F.7 Your boiler is currently unable to heat your domestic hot water, meaning you will not have any hot water available from your taps or shower.
Your boiler is currently unable to heat your domestic hot water, meaning you will not have any hot water available from your taps or shower.
Parts commonly replaced
- DHW temperature sensor
- Diverter valve motor
- Diverter valve cartridge
Related codes
F.8 Your boiler is currently unable to heat your domestic hot water, meaning you will not have hot water available from your taps or shower.
Your boiler is currently unable to heat your domestic hot water, meaning you will not have hot water available from your taps or shower.
Parts commonly replaced
- DHW temperature sensor
- Diverter valve
- PCB
Related codes
F.9 Your boiler has lost connection with the sensor that monitors your hot water temperature, which usually means it cannot heat your water safely or at all.
Your boiler has lost connection with the sensor that monitors your hot water temperature, which usually means it cannot heat your water safely or at all.
Parts commonly replaced
- DHW Outlet Temperature Sensor (NTC)
- Wiring harness / lead connector
Related codes
F.10 Your boiler has identified a technical fault with the sensor that monitors your hot water temperature, which typically means you will not have reliable hot water.
Your boiler has identified a technical fault with the sensor that monitors your hot water temperature, which typically means you will not have reliable hot water.
Parts commonly replaced
- DHW outlet temperature sensor (NTC)
- Wiring harness / lead
Related codes
F.11 Your boiler is not detecting heat coming from your solar thermal panels, so it cannot use that energy to help warm your home or water.
Your boiler is not detecting heat coming from your solar thermal panels, so it cannot use that energy to help warm your home or water.
Parts commonly replaced
- Solar collector temperature sensor
- Cylinder temperature sensor
- Solar circuit pump
Related codes
F.12 Your boiler has detected that the solar thermal panels connected to your heating system are not currently producing hot water as expected.
Your boiler has detected that the solar thermal panels connected to your heating system are not currently producing hot water as expected.
Parts commonly replaced
- Solar collector sensor
- Solar pump
- Flow sensor
Related codes
F.13 Your boiler has lost its connection to the sensor that measures the temperature outside, meaning it may not know how hard it needs to work to heat your home.
Your boiler has lost its connection to the sensor that measures the temperature outside, meaning it may not know how hard it needs to work to heat your home.
What to check first
- Check the outside sensor for any obvious signs of physical damage or loose casing
- Inspect the visible cable running from the sensor for any breaks or animal damage
- Try resetting the boiler to see if the fault clears (it may be a temporary software glitch)
Parts commonly replaced
- Outdoor temperature sensor
- Sensor wiring/cabling
Related codes
F.14 Your boiler is struggling to work out how hard to run because its external weather thermometer has developed an electrical fault.
Your boiler is struggling to work out how hard to run because its external weather thermometer has developed an electrical fault.
Parts commonly replaced
- Outside temperature sensor
- Sensor wiring cable
Related codes
F.15 Your boiler has lost the ability to communicate with or receive heat from your solar thermal panels, meaning it cannot use free energy from the sun to help heat your water.
Your boiler has lost the ability to communicate with or receive heat from your solar thermal panels, meaning it cannot use free energy from the sun to help heat your water.
Parts commonly replaced
- Solar collector temperature sensor
- Solar pump module
- Communication cable
Related codes
F.16 Your boiler is reporting that it is not receiving heat from your solar thermal panels to warm your hot water tank as expected.
Your boiler is reporting that it is not receiving heat from your solar thermal panels to warm your hot water tank as expected.
Parts commonly replaced
- Solar circuit temperature sensor
- Solar pump
- Solar fluid
Related codes
F.29 Your boiler has lost communication with a sensor that monitors the water temperature in your heating system's distribution hub.
Your boiler has lost communication with a sensor that monitors the water temperature in your heating system's distribution hub.
Parts commonly replaced
- Low loss header temperature sensor (NTC)
- Sensor wiring harness
Related codes
F.30 Your boiler has detected a technical fault with a sensor that monitors water temperature elsewhere in your heating system, which is preventing the boiler from running correctly.
Your boiler has detected a technical fault with a sensor that monitors water temperature elsewhere in your heating system, which is preventing the boiler from running correctly.
Parts commonly replaced
- Low loss header temperature sensor (NTC)
- Sensor wiring harness
- External system control module
Related codes
F.49 Your boiler has detected a persistent issue with the burner and has automatically shut itself down to prevent unsafe operation.
Your boiler has detected a persistent issue with the burner and has automatically shut itself down to prevent unsafe operation.
Parts commonly replaced
- Ionisation electrode
- Gas valve
- Ignition transformer
- Control board
Related codes
F.50 Your boiler has detected an internal issue and has safely shut itself down to prevent damage, meaning you currently have no heating or hot water.
Your boiler has detected an internal issue and has safely shut itself down to prevent damage, meaning you currently have no heating or hot water.
Parts commonly replaced
- Gas valve
- Ignition electrode
- Control board (PCB)
Related codes
F.57 Your boiler is currently ignoring the temperature settings from your wall thermostat and is running based solely on the weather outside or its own internal default settings.
Your boiler is currently ignoring the temperature settings from your wall thermostat and is running based solely on the weather outside or its own internal default settings.
Parts commonly replaced
- External temperature sensor
- Communication module
- Control unit PCB
Related codes
F.58 Your boiler is operating in a basic mode because it has lost the signal from your room thermostat, meaning it cannot adjust its temperature based on how warm your home is.
Your boiler is operating in a basic mode because it has lost the signal from your room thermostat, meaning it cannot adjust its temperature based on how warm your home is.
Parts commonly replaced
- Bus communication module
- Room thermostat unit
- Wiring harness
Related codes
F.59 Your boiler has stopped working because it isn't receiving enough electrical power to operate the burner safely.
Your boiler has stopped working because it isn't receiving enough electrical power to operate the burner safely.
Parts commonly replaced
- PCB (Printed Circuit Board)
- Internal Wiring Harness
- Low Voltage Transformer
Related codes
F.62 Your boiler has detected an internal error during the ignition process and has safely shut down to prevent it from firing improperly.
Your boiler has detected an internal error during the ignition process and has safely shut down to prevent it from firing improperly.
Parts commonly replaced
- Gas valve
- Burner control unit
- Ignition electrode
Related codes
F.63 Your boiler has detected a critical internal error in its main electronic control unit, causing it to shut down to prevent unsafe operation.
Your boiler has detected a critical internal error in its main electronic control unit, causing it to shut down to prevent unsafe operation.
Parts commonly replaced
- Control unit (PCB)
- Wiring harness
Related codes
F.67 Your boiler has detected an internal issue with the burner flame signal, causing it to shut down for safety reasons to prevent improper combustion.
Your boiler has detected an internal issue with the burner flame signal, causing it to shut down for safety reasons to prevent improper combustion.
Parts commonly replaced
- Ionisation electrode
- Gas valve
- Boiler control unit (PCB)
Related codes
F.68 Your boiler has detected an issue with the flame stability or air-gas supply and has shut down for safety.
Your boiler has detected an issue with the flame stability or air-gas supply and has shut down for safety.
Parts commonly replaced
- Gas valve
- Fan
- Ionisation electrode
- Air intake/flue seal
Related codes
F.69 Your boiler has detected an internal issue and shut itself down as a safety precaution, meaning you currently have no heating or hot water.
Your boiler has detected an internal issue and shut itself down as a safety precaution, meaning you currently have no heating or hot water.
Parts commonly replaced
- Ionization electrode
- Gas valve
- Burner control unit
Related codes
F.70 Your boiler's electronic control unit is experiencing an internal error and has safely shut down the system to prevent further issues.
Your boiler's electronic control unit is experiencing an internal error and has safely shut down the system to prevent further issues.
Parts commonly replaced
- Main control board (PCB)
- Communication module
Related codes
F.71 Your boiler has detected an internal issue with its temperature monitoring system and has automatically shut down to prevent damage.
Your boiler has detected an internal issue with its temperature monitoring system and has automatically shut down to prevent damage.
Parts commonly replaced
- Flow temperature sensor
- Return temperature sensor
- Main PCB
Related codes
F.72 Your boiler has detected an issue with the temperature sensors that monitor the heating process, causing it to shut down for safety.
Your boiler has detected an issue with the temperature sensors that monitor the heating process, causing it to shut down for safety.
Parts commonly replaced
- Flow temperature sensor
- Return temperature sensor
- Main PCB
Related codes
F.73 Your boiler has detected an internal issue with the water pressure sensor, which is preventing it from safely lighting the burner.
Your boiler has detected an internal issue with the water pressure sensor, which is preventing it from safely lighting the burner.
Parts commonly replaced
- Pressure sensor
- Wiring harness
Related codes
F.74 Your boiler has detected that the water pressure in the system is too low to operate safely, causing it to shut down to prevent damage.
Your boiler has detected that the water pressure in the system is too low to operate safely, causing it to shut down to prevent damage.
What to check first
- Locate the external filling loop (usually a silver flexible hose under or near the boiler).
- Open the one or two taps on the filling loop slowly until you see the pressure gauge rise.
- Close the taps tight once the pressure reaches 1.5 bar, then reset the boiler.
Parts commonly replaced
- Filling loop valves
- Expansion vessel
- Pressure sensor
Related codes
F.77 Your boiler's internal computer brain is having trouble reading or saving its settings, causing the system to stop working for safety.
Your boiler's internal computer brain is having trouble reading or saving its settings, causing the system to stop working for safety.
Parts commonly replaced
- Electronic Control Unit (PCB)
- HMI (Control Unit) Programming Key
Related codes
F.89 Your boiler has detected an internal communication error between its main control components, causing it to shut down for safety.
Your boiler has detected an internal communication error between its main control components, causing it to shut down for safety.
Parts commonly replaced
- Control unit
- Wiring harness
- Communication module
Related codes
F.91 Your boiler has detected an issue with an external accessory or control module and is running in a limited backup mode to keep you warm until it can be properly checked.
Your boiler has detected an issue with an external accessory or control module and is running in a limited backup mode to keep you warm until it can be properly checked.
Parts commonly replaced
- Extension module
- Communication cable
- PCB
Related codes
F.92 Your boiler's internal computer brain is struggling to talk to one of its electronic control parts, causing the system to stop working.
Your boiler's internal computer brain is struggling to talk to one of its electronic control parts, causing the system to stop working.
Parts commonly replaced
- ADIO Electronics Module
- Wiring Harness
- Main PCB
Related codes
F.94 Your boiler's internal computer parts have stopped communicating with each other, preventing the system from operating correctly.
Your boiler's internal computer parts have stopped communicating with each other, preventing the system from operating correctly.
Parts commonly replaced
- SDIO Electronics Module
- SM1A Extension Module
- Internal Wiring Harness
Related codes
F.100 Your boiler has stopped working because of a communication failure between its internal electronic parts, meaning the main controls can no longer talk to each other.
Your boiler has stopped working because of a communication failure between its internal electronic parts, meaning the main controls can no longer talk to each other.
Parts commonly replaced
- Electronic Control PCB
- PlusBus Wiring Loom
- External Sensor Module
Related codes
F.104 Your boiler has detected an error with an external electronic add-on, meaning it is unsure how to control certain heating or hot water features.
Your boiler has detected an error with an external electronic add-on, meaning it is unsure how to control certain heating or hot water features.
Parts commonly replaced
- EM-EA1 extension module
- Communication cable
- Main PCB
Related codes
F.142 Your boiler has detected an internal issue and has safely shut itself down to prevent damage, meaning you currently have no heating or hot water.
Your boiler has detected an internal issue and has safely shut itself down to prevent damage, meaning you currently have no heating or hot water.
Parts commonly replaced
- Ionisation electrode
- Ignition transformer
- Main control board
Related codes
F.160 Your boiler has detected an issue preventing it from lighting the flame, which means your heating and hot water have stopped working.
Your boiler has detected an issue preventing it from lighting the flame, which means your heating and hot water have stopped working.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Ionisation probe
- Control unit
Related codes
F.161 Your boiler has detected an issue with the burning process and has shut itself down to keep your home safe.
Your boiler has detected an issue with the burning process and has shut itself down to keep your home safe.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Ionisation probe
- Control board
Related codes
F.163 Your boiler has detected an issue with the burner process and has shut itself down as a safety precaution to prevent further faults.
Your boiler has detected an issue with the burner process and has shut itself down as a safety precaution to prevent further faults.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Burner assembly
Related codes
F.182 Your boiler is currently unable to heat your domestic hot water, meaning you will likely have no hot water coming out of your taps.
Your boiler is currently unable to heat your domestic hot water, meaning you will likely have no hot water coming out of your taps.
Parts commonly replaced
- DHW diverter valve
- DHW flow sensor
- DHW pump
Related codes
F.183 Your boiler has stopped heating your hot water supply, meaning your taps and shower will only run cold.
Your boiler has stopped heating your hot water supply, meaning your taps and shower will only run cold.
Parts commonly replaced
- Diverter valve motor
- DHW sensor
- Flow switch
Related codes
F.184 Your boiler has detected an internal error preventing the burner from lighting, which means your heating and hot water will not work until the fault is cleared.
Your boiler has detected an internal error preventing the burner from lighting, which means your heating and hot water will not work until the fault is cleared.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Control unit
Related codes
F.185 Your boiler has detected an internal error preventing the burner from lighting, which means your heating and hot water will not work until the fault is cleared.
Your boiler has detected an internal error preventing the burner from lighting, which means your heating and hot water will not work until the fault is cleared.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Control unit (PCB)
- Flame rectification sensor
Related codes
F.299 Your boiler has lost its internal time and date settings, which may disrupt your heating schedules.
Your boiler has lost its internal time and date settings, which may disrupt your heating schedules.
What to check first
- Locate the control panel on the front of the boiler
- Navigate to the 'Settings' menu using the touchscreen
- Select 'Time and Date' and manually update them to the current values
- Confirm the changes and check if the fault code clears
Parts commonly replaced
- HMI Touchscreen Control Unit
- Internal backup battery
Related codes
F.342 Your boiler has detected an internal communication error between its main control components, causing it to shut down for safety.
Your boiler has detected an internal communication error between its main control components, causing it to shut down for safety.
Parts commonly replaced
- Main PCB
- Communication cable
- Control unit
Related codes
F.345 Your boiler has automatically shut down because it has detected that the internal water temperature has become dangerously high.
Your boiler has automatically shut down because it has detected that the internal water temperature has become dangerously high.
What to check first
- Check that all radiator valves are fully open and not turned off.
- Ensure the external magnetic filter is clean and not blocked.
- Press the 'Reset' button on the boiler control panel once to see if the system restarts.
Parts commonly replaced
- High limit thermostat
- Circulation pump
- Overheat sensor (NTC)
Related codes
F.346 Your boiler has detected an internal issue and has safely shut itself down to prevent operation while it is not functioning correctly.
Your boiler has detected an internal issue and has safely shut itself down to prevent operation while it is not functioning correctly.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Ionisation probe
- Control board
Related codes
F.348 Your boiler has detected an issue with the internal combustion process and has safely shut itself down to prevent unsafe operation.
Your boiler has detected an issue with the internal combustion process and has safely shut itself down to prevent unsafe operation.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Ionisation probe
- Control board
Related codes
F.349 Your boiler has detected a problem with the burner operation and has automatically shut itself down for safety reasons.
Your boiler has detected a problem with the burner operation and has automatically shut itself down for safety reasons.
Parts commonly replaced
- Ignition electrode
- Ionisation electrode
- Gas valve
- Control board
Related codes
F.350 Your boiler has detected an internal issue and has safely shut itself down to prevent damage, meaning you currently have no heating or hot water.
Your boiler has detected an internal issue and has safely shut itself down to prevent damage, meaning you currently have no heating or hot water.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Control board
Related codes
F.351 Your boiler has detected an internal issue and has safely shut itself down to prevent any potential safety hazards.
Your boiler has detected an internal issue and has safely shut itself down to prevent any potential safety hazards.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Control unit (PCB)
Related codes
F.352 Your boiler has detected an issue with the burner ignition or combustion process and has shut itself down as a safety precaution.
Your boiler has detected an issue with the burner ignition or combustion process and has shut itself down as a safety precaution.
Parts commonly replaced
- Ignition electrode
- Ionisation electrode
- Gas valve
- Control unit
Related codes
F.353 Your boiler has detected a minor inconsistency in the internal combustion process and is temporarily pausing to restart safely.
Your boiler has detected a minor inconsistency in the internal combustion process and is temporarily pausing to restart safely.
Parts commonly replaced
- Ionisation electrode
- Ignition lead
- Gas valve
Related codes
F.354 Your boiler has detected an issue that prevents the burner from igniting, meaning your heating and hot water will not work until this is cleared.
Your boiler has detected an issue that prevents the burner from igniting, meaning your heating and hot water will not work until this is cleared.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Ionisation probe
- Control board
Related codes
F.355 Your boiler has detected a flame before it has even started the ignition process, which is a safety conflict that prevents the system from running.
Your boiler has detected a flame before it has even started the ignition process, which is a safety conflict that prevents the system from running.
Parts commonly replaced
- Ionisation electrode
- Ignition lead
- Burner control unit (PCB)
Related codes
F.357 Your boiler has detected an internal issue and has safely shut itself down to prevent further problems.
Your boiler has detected an internal issue and has safely shut itself down to prevent further problems.
Parts commonly replaced
- Gas valve
- Ignition electrode
- Burner gasket
- Control board
Related codes
F.359 Your boiler has detected an internal issue and has safely shut down the burner to prevent further problems.
Your boiler has detected an internal issue and has safely shut down the burner to prevent further problems.
Parts commonly replaced
- Ionisation electrode
- Ignition transformer
- Gas valve
- Main PCB
Related codes
F.361 Your boiler is struggling to detect a flame when it tries to start, which means it cannot fire up to provide heating or hot water.
Your boiler is struggling to detect a flame when it tries to start, which means it cannot fire up to provide heating or hot water.
What to check first
- Check that your gas emergency control valve is in the 'on' position
- If you have a pre-payment meter, check that you have sufficient credit
- Press the 'Reset' button on the boiler control panel once
Parts commonly replaced
- Ignition electrode
- Ionisation probe
- Gas valve
Related codes
F.365 Your boiler has detected that the burner is not firing correctly, which has caused it to stop working to prevent any potential safety issues.
Your boiler has detected that the burner is not firing correctly, which has caused it to stop working to prevent any potential safety issues.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Ionisation probe
- Main control board
Related codes
F.366 Your boiler has stopped working because it failed to light or maintain a flame correctly, so it has shut itself down for safety reasons.
Your boiler has stopped working because it failed to light or maintain a flame correctly, so it has shut itself down for safety reasons.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Ionisation probe
- Control board
Related codes
F.367 Your boiler has detected an issue with the burning process and has automatically shut down to keep your home safe.
Your boiler has detected an issue with the burning process and has automatically shut down to keep your home safe.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Ventilation/flue components
Related codes
F.369 Your boiler has detected an internal issue with the combustion system and has safely shut itself down to prevent damage or safety hazards.
Your boiler has detected an internal issue with the combustion system and has safely shut itself down to prevent damage or safety hazards.
Parts commonly replaced
- Gas valve
- Burner assembly
- Ignition electrode
- Main circuit board
Related codes
F.370 Your boiler has detected a general issue preventing it from firing up, which means you currently have no central heating or hot water.
Your boiler has detected a general issue preventing it from firing up, which means you currently have no central heating or hot water.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Control board
Related codes
F.372 Your boiler has detected an issue with the burner preventing it from firing, meaning your heating and hot water will not be working.
Your boiler has detected an issue with the burner preventing it from firing, meaning your heating and hot water will not be working.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Ionisation probe
- Control unit
Related codes
F.373 Your boiler has detected an internal issue and has safely shut down the burner to prevent damage, meaning you currently have no heating or hot water.
Your boiler has detected an internal issue and has safely shut down the burner to prevent damage, meaning you currently have no heating or hot water.
Parts commonly replaced
- Ignition electrode
- Ionisation electrode
- Gas valve
- Control board
Related codes
F.377 Your boiler has detected an internal issue and has safely shut itself down to prevent damage, meaning you currently have no heating or hot water.
Your boiler has detected an internal issue and has safely shut itself down to prevent damage, meaning you currently have no heating or hot water.
Parts commonly replaced
- Gas valve
- Control unit
- Ignition electrode
Related codes
F.378 Your boiler has detected an internal issue with the combustion process and has stopped working to keep your home safe.
Your boiler has detected an internal issue with the combustion process and has stopped working to keep your home safe.
Parts commonly replaced
- Gas valve
- Burner assembly
- Control unit
Related codes
F.379 Your boiler has detected an issue with the internal combustion process and has safely shut itself down to prevent any further problems.
Your boiler has detected an issue with the internal combustion process and has safely shut itself down to prevent any further problems.
Parts commonly replaced
- Ionisation electrode
- Ignition transformer
- Gas valve
Related codes
F.380 Your boiler has detected a general issue with its internal combustion process and has safely shut itself down to prevent potential damage.
Your boiler has detected a general issue with its internal combustion process and has safely shut itself down to prevent potential damage.
Parts commonly replaced
- Ignition electrode
- Ionisation probe
- Gas valve
- Control unit
Related codes
F.381 Your boiler has detected a general issue within the burner system and has automatically shut down to prevent further problems.
Your boiler has detected a general issue within the burner system and has automatically shut down to prevent further problems.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Ionisation probe
- Control unit
Related codes
F.382 Your boiler has detected a problem with the burner's operation and has safely shut itself down to prevent potential issues.
Your boiler has detected a problem with the burner's operation and has safely shut itself down to prevent potential issues.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Ionisation probe
- Control board
Related codes
F.383 Your boiler has detected an internal issue that is preventing the burner from igniting, meaning you currently have no heating or hot water.
Your boiler has detected an internal issue that is preventing the burner from igniting, meaning you currently have no heating or hot water.
Parts commonly replaced
- Ionisation electrode
- Ignition transformer
- Gas valve
- Main PCB
Related codes
F.384 Your boiler has detected an internal issue and has safely shut itself down to prevent any potential risks.
Your boiler has detected an internal issue and has safely shut itself down to prevent any potential risks.
Parts commonly replaced
- Control unit
- Ignition module
- Wiring harness
Related codes
F.385 Your boiler has detected an internal issue and has shut itself down as a safety precaution to prevent damage.
Your boiler has detected an internal issue and has shut itself down as a safety precaution to prevent damage.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Control board (PCB)
Related codes
F.386 Your boiler has detected an internal issue and has safely shut itself down to prevent potential damage, meaning you currently have no heating or hot water.
Your boiler has detected an internal issue and has safely shut itself down to prevent potential damage, meaning you currently have no heating or hot water.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Control unit PCB
- Ionization probe
Related codes
F.387 Your boiler has detected an internal issue that is preventing the burner from igniting, meaning your heating and hot water will not work until the fault is cleared.
Your boiler has detected an internal issue that is preventing the burner from igniting, meaning your heating and hot water will not work until the fault is cleared.
Parts commonly replaced
- Ignition electrode
- Ionisation electrode
- Gas valve
Related codes
F.388 Your boiler has detected a general issue with the burner and has safely shut itself down to prevent further problems.
Your boiler has detected a general issue with the burner and has safely shut itself down to prevent further problems.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Ionisation electrode
Related codes
F.395 Your boiler has detected an issue with the burner and has safely shut itself down to prevent potential damage or unsafe operation.
Your boiler has detected an issue with the burner and has safely shut itself down to prevent potential damage or unsafe operation.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Ionisation probe
- Control board
Related codes
F.396 Your boiler has detected an issue with the burner process and has shut itself down as a safety precaution to prevent unsafe operation.
Your boiler has detected an issue with the burner process and has shut itself down as a safety precaution to prevent unsafe operation.
Parts commonly replaced
- Ionisation electrode
- Ignition transformer
- Gas valve
- Control unit
Related codes
F.399 Your boiler has detected an internal error preventing the burner from lighting, which means your heating and hot water will not work until the fault is cleared.
Your boiler has detected an internal error preventing the burner from lighting, which means your heating and hot water will not work until the fault is cleared.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Control board
Related codes
F.400 Your boiler has detected a general issue with the burner's operation and has safely shut itself down to prevent further problems.
Your boiler has detected a general issue with the burner's operation and has safely shut itself down to prevent further problems.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Ionisation probe
- Control unit
Related codes
F.401 Your boiler has stopped heating because the burner has detected a safety fault and shut itself down to prevent any damage.
Your boiler has stopped heating because the burner has detected a safety fault and shut itself down to prevent any damage.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Ionisation electrode
Related codes
F.402 Your boiler has detected an issue with the burning process and has automatically shut down for safety reasons to prevent it from operating incorrectly.
Your boiler has detected an issue with the burning process and has automatically shut down for safety reasons to prevent it from operating incorrectly.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Ionisation probe
- Control board
Related codes
F.403 Your boiler has detected an internal issue with the burner and has safely shut itself down to prevent further problems.
Your boiler has detected an internal issue with the burner and has safely shut itself down to prevent further problems.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Ionisation probe
- Control unit
Related codes
F.404 Your boiler has detected an issue with the combustion process and has safely shut down to prevent unsafe operation.
Your boiler has detected an issue with the combustion process and has safely shut down to prevent unsafe operation.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Burner gasket
Related codes
F.405 Your boiler has detected an issue with the combustion process and has safely shut itself down to prevent it from running incorrectly.
Your boiler has detected an issue with the combustion process and has safely shut itself down to prevent it from running incorrectly.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Burner assembly
- Ionisation probe
Related codes
F.406 Your boiler has detected an issue with the burner process and has shut down to keep your home safe.
Your boiler has detected an issue with the burner process and has shut down to keep your home safe.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Ionisation probe
- Control board
Related codes
F.408 Your boiler has detected an internal issue that is preventing it from lighting safely, so it has shut down to protect your home.
Your boiler has detected an internal issue that is preventing it from lighting safely, so it has shut down to protect your home.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Control board (PCB)
Related codes
F.410 Your boiler's main internal computer has encountered a critical processing error and can no longer control the burner safely.
Your boiler's main internal computer has encountered a critical processing error and can no longer control the burner safely.
Parts commonly replaced
- BCU Burner Control Unit
- HMI Operator Unit
- Main PCB
Related codes
F.416 Your boiler has shut down because it detects that a safety sensor meant to monitor exhaust fumes is loose or installed incorrectly.
Your boiler has shut down because it detects that a safety sensor meant to monitor exhaust fumes is loose or installed incorrectly.
Parts commonly replaced
- Flue gas temperature sensor
- Sensor retaining clip
Related codes
F.417 Your boiler has detected an internal issue and has automatically shut itself down for safety reasons to prevent further damage.
Your boiler has detected an internal issue and has automatically shut itself down for safety reasons to prevent further damage.
Parts commonly replaced
- Ionisation electrode
- Gas valve
- Control unit
Related codes
F.418 Your boiler has stopped working because its internal computer has lost power or has a broken electrical connection.
Your boiler has stopped working because its internal computer has lost power or has a broken electrical connection.
Parts commonly replaced
- Low voltage wiring harness
- External Power Supply Unit
- Main PCB
Related codes
F.425 Your boiler's internal computer is having difficulty processing its programmed settings, causing it to pause operations to prevent incorrect function.
Your boiler's internal computer is having difficulty processing its programmed settings, causing it to pause operations to prevent incorrect function.
Parts commonly replaced
- Main PCB
- Control unit
Related codes
F.430 Your boiler is currently operating normally under automated control settings, and this code is simply a status message confirming it is working as expected.
Your boiler is currently operating normally under automated control settings, and this code is simply a status message confirming it is working as expected.
What to check first
- Check your boiler display for any actual error symbols.
- If no other issues are present, no action is required.
- Restart the boiler using the power button if you wish to clear the notification.
Related codes
F.446 Your boiler has detected an issue with the burner's ability to stay lit or ignite correctly and has shut down for your safety.
Your boiler has detected an issue with the burner's ability to stay lit or ignite correctly and has shut down for your safety.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Ionisation probe
- Burner gasket
Related codes
F.447 Your boiler has detected an internal error that has forced it to stop heating to ensure your home remains safe.
Your boiler has detected an internal error that has forced it to stop heating to ensure your home remains safe.
Parts commonly replaced
- Control unit
- Gas valve
- Ignition electrode
Related codes
F.448 Your boiler has detected an issue with the combustion process or burner ignition and has safely shut itself down to prevent further problems.
Your boiler has detected an issue with the combustion process or burner ignition and has safely shut itself down to prevent further problems.
Parts commonly replaced
- Ignition electrode
- Ionisation probe
- Gas valve
- Control unit
Related codes
F.449 Your boiler has detected an issue with the burning process and has automatically shut itself down for safety reasons.
Your boiler has detected an issue with the burning process and has automatically shut itself down for safety reasons.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Burner gasket
Related codes
F.450 Your boiler has detected an issue with the burner's operation and has safely shut itself down to prevent potential damage.
Your boiler has detected an issue with the burner's operation and has safely shut itself down to prevent potential damage.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Ionisation probe
- Control unit
Related codes
F.451 Your boiler has detected an issue with the combustion process and has safely shut down to prevent it from running incorrectly.
Your boiler has detected an issue with the combustion process and has safely shut down to prevent it from running incorrectly.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Ionisation probe
- Control unit
Related codes
F.452 Your boiler has detected an issue with the burner process and has shut itself down as a safety precaution to prevent further faults.
Your boiler has detected an issue with the burner process and has shut itself down as a safety precaution to prevent further faults.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Burner control unit
Related codes
F.453 Your boiler has detected a persistent issue with the combustion process and has safely shut itself down to prevent unsafe operation.
Your boiler has detected a persistent issue with the combustion process and has safely shut itself down to prevent unsafe operation.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Burner gasket
- Control board
Related codes
F.454 Your boiler has detected an internal issue with the burner and has safely shut itself down to prevent operation while it is not functioning correctly.
Your boiler has detected an internal issue with the burner and has safely shut itself down to prevent operation while it is not functioning correctly.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Burner control unit
Related codes
F.455 Your boiler has detected an internal issue with the burner and has safely shut itself down to prevent further problems.
Your boiler has detected an internal issue with the burner and has safely shut itself down to prevent further problems.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Ionisation probe
- Control unit
Related codes
F.456 Your boiler has detected an issue with the combustion process and has safely shut itself down to prevent unsafe operation.
Your boiler has detected an issue with the combustion process and has safely shut itself down to prevent unsafe operation.
Parts commonly replaced
- Ignition electrode
- Flame rectification probe
- Gas valve
- Control board
Related codes
F.457 Your boiler has stopped working because it has detected an internal issue and triggered a safety shutdown to prevent further problems.
Your boiler has stopped working because it has detected an internal issue and triggered a safety shutdown to prevent further problems.
Parts commonly replaced
- Ionisation electrode
- Ignition transformer
- Printed circuit board
Related codes
F.458 Your boiler has stopped working because it has detected an internal issue and shut itself down for safety reasons.
Your boiler has stopped working because it has detected an internal issue and shut itself down for safety reasons.
Parts commonly replaced
- Ionisation electrode
- Ignition transformer
- Main PCB
Related codes
F.462 Your boiler has detected a general issue within its internal combustion system and has safely shut itself down to prevent further damage.
Your boiler has detected a general issue within its internal combustion system and has safely shut itself down to prevent further damage.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Main circuit board (PCB)
- Ionization probe
Related codes
F.463 Your boiler has detected an issue with the burner's operation and has safely shut itself down to prevent potential problems.
Your boiler has detected an issue with the burner's operation and has safely shut itself down to prevent potential problems.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Ionisation probe
- Control board
Related codes
F.464 Your boiler has detected an issue with the burner process and has shut itself down as a safety precaution to prevent further faults.
Your boiler has detected an issue with the burner process and has shut itself down as a safety precaution to prevent further faults.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Ionisation probe
- Control board
Related codes
F.467 Your boiler has detected an issue with the burner ignition or combustion process and has safely shut itself down to prevent further problems.
Your boiler has detected an issue with the burner ignition or combustion process and has safely shut itself down to prevent further problems.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Ionisation probe
- Control board
Related codes
F.468 Your boiler has detected an issue with the burner and has safely shut itself down to prevent further problems.
Your boiler has detected an issue with the burner and has safely shut itself down to prevent further problems.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Ionisation probe
- PCB
Related codes
F.471 Your boiler is currently idle because it is not receiving a signal from your thermostat or hot water controller to provide heat.
Your boiler is currently idle because it is not receiving a signal from your thermostat or hot water controller to provide heat.
Parts commonly replaced
- External controls
- Wiring centre
- Main PCB
Related codes
F.473 Your boiler is currently idle because it is not receiving a signal from your thermostat or heating controls to start producing heat.
Your boiler is currently idle because it is not receiving a signal from your thermostat or heating controls to start producing heat.
What to check first
- Check that your room thermostat or smart controller is set to a temperature higher than the current room temperature.
- Ensure your heating programmer or timer is set to 'On' or in a timed period.
- Check if your thermostat batteries need replacing or if your internet-connected controller has lost its Wi-Fi connection.
Parts commonly replaced
- External heating controller
- Thermostat
- Bus communication module
Related codes
F.474 Your boiler has detected an internal issue and shut down for safety to prevent damage, meaning you currently have no heating or hot water.
Your boiler has detected an internal issue and shut down for safety to prevent damage, meaning you currently have no heating or hot water.
Parts commonly replaced
- Ionisation electrode
- Ignition transformer
- Main control board
Related codes
F.517 Your boiler is struggling to communicate with its external control panel or thermostat, which may prevent it from receiving instructions to turn on your heating or hot water.
Your boiler is struggling to communicate with its external control panel or thermostat, which may prevent it from receiving instructions to turn on your heating or hot water.
Parts commonly replaced
- Communication Module
- Vitotrol Control Unit
- System Wiring Harness
Related codes
F.527 Your boiler has detected an internal issue with the burner ignition process and has safely shut itself down to prevent any unsafe operation.
Your boiler has detected an internal issue with the burner ignition process and has safely shut itself down to prevent any unsafe operation.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Burner control unit
Related codes
F.528 Your boiler has detected an issue with the combustion process and has safely shut itself down to prevent unsafe operation.
Your boiler has detected an issue with the combustion process and has safely shut itself down to prevent unsafe operation.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Control unit
Related codes
F.530 Your boiler has detected that the solar heating panels connected to your system are not operating at full efficiency.
Your boiler has detected that the solar heating panels connected to your system are not operating at full efficiency.
Parts commonly replaced
- Solar temperature sensor
- Solar pump
- Solar circuit pressure gauge
Related codes
F.540 Your boiler has detected an issue with the burner and has safely shut itself down to prevent unsafe operation.
Your boiler has detected an issue with the burner and has safely shut itself down to prevent unsafe operation.
Parts commonly replaced
- Ionisation electrode
- Ignition transformer
- Gas valve
Related codes
F.544 Your boiler has detected an issue with the valve that regulates the temperature of your heating water, so it has shut that valve to protect your system while keeping the water pump running.
Your boiler has detected an issue with the valve that regulates the temperature of your heating water, so it has shut that valve to protect your system while keeping the water pump running.
Parts commonly replaced
- Mixing valve motor
- Mixing valve assembly
- Heating circuit control board
Related codes
F.545 Your boiler has detected an issue with the valve that regulates your heating temperature, causing it to shut down to prevent the system from getting too hot.
Your boiler has detected an issue with the valve that regulates your heating temperature, causing it to shut down to prevent the system from getting too hot.
Parts commonly replaced
- Mixing valve motor
- Mixing valve actuator
- Heating circuit control board
Related codes
F.546 Your boiler has detected that the mixing valve is not positioning correctly, which may lead to your radiators failing to reach the desired temperature.
Your boiler has detected that the mixing valve is not positioning correctly, which may lead to your radiators failing to reach the desired temperature.
Parts commonly replaced
- Mixing valve actuator
- Mixing valve assembly
- PCB
Related codes
F.547 Your boiler has detected that the valve controlling the water temperature to your radiators has closed, which means your heating may not get as warm as you have set it.
Your boiler has detected that the valve controlling the water temperature to your radiators has closed, which means your heating may not get as warm as you have set it.
Parts commonly replaced
- Mixing valve actuator
- Mixing valve motor
- Temperature sensor
Related codes
F.548 Your boiler has detected that the mixing valve is not operating correctly, which may lead to your radiators not reaching the desired temperature.
Your boiler has detected that the mixing valve is not operating correctly, which may lead to your radiators not reaching the desired temperature.
Parts commonly replaced
- Mixing valve motor
- Mixing valve cartridge
- Heating circuit control board
Related codes
F.549 Your boiler has detected an issue with the valve that regulates your heating temperature, causing it to shut off to prevent water from becoming too hot.
Your boiler has detected an issue with the valve that regulates your heating temperature, causing it to shut off to prevent water from becoming too hot.
Parts commonly replaced
- Mixing valve actuator
- Mixing valve assembly
- Temperature sensor
Related codes
I.57 Your boiler has been temporarily stopped by an external device, such as a smart thermostat or a safety switch, which is telling the system not to run.
Your boiler has been temporarily stopped by an external device, such as a smart thermostat or a safety switch, which is telling the system not to run.
What to check first
- Check if your room thermostat or heating app is set higher than the current room temperature.
- Ensure any external switches or safety devices connected to the boiler are in the 'On' position.
- Restart the boiler using its power button to see if the external demand clears.
Parts commonly replaced
- External Thermostat
- Wiring Centre
- Smart Control Hub
Related codes
Status & diagnostic codes 8 operating states & engineer diagnostics
Not faults — these are normal operating states. Tap to expand.
8 operating states & engineer diagnostics
Not faults — these are normal operating states. Tap to expand.
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