124 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
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Your boiler's control panel and its internal computer are not talking to each other, meaning the unit cannot receive instructions to provide heat or hot water.
Your boiler is simply displaying a status message telling you it is automatically adjusting its power output to best heat your home, rather than indicating a fault.
Your boiler is simply performing a routine safety cycle to circulate leftover warm water after the heating has switched off, which is a normal part of its operation.
Your boiler is currently taking a mandatory rest period to prevent it from switching on and off too frequently, which is a normal protective feature.
This code is simply an information display showing the current temperature of the water inside your hot water storage cylinder.
The d.05 code is not actually an error; it is a normal status message showing the temperature your boiler is currently aiming to reach for your radiators.
Your boiler is simply displaying the temperature setting currently programmed for your hot water, rather than indicating a system fault.
This code is simply an information display showing the temperature setting currently requested for your hot water tank rather than a system fault.
Your boiler is currently receiving a signal from your room thermostat telling it that no heating is required at this moment.
This is not a fault; it is simply a status message showing the current target temperature your thermostat is requesting from your boiler.
Your boiler is simply reporting the current activity status of its internal water pump to let you know if it is turned on or off.
Your boiler is simply reporting that a secondary pump, responsible for circulating water through your heating system, is currently not running.
Your boiler is simply reporting that the internal pump responsible for moving hot water is currently resting or has just switched on.
This code indicates your boiler's internal water pump speed setting, rather than a system fault or breakdown.
This code is not an actual fault; it is simply showing you the current operating speed of your boiler's internal water pump.
Your boiler is correctly receiving a signal from your thermostat that the heating is currently turned off.
Your boiler is currently configured to monitor the temperature of water returning from your heating system rather than the water leaving it, which is a specific setting typically used for underfloor heating systems.
This code is simply an information status display showing how your boiler's internal water pump is currently being told to operate, rather than an error or a fault with your heating system.
This code is not actually an error; it is a status message showing the current setting for your maximum hot water temperature.
This is not a fault; it simply indicates whether the comfort setting that keeps your tap water ready to heat instantly is currently turned on or off.
Your boiler is simply reporting that it is currently not being asked to produce any hot water.
Your boiler is simply reporting that it is currently set to standby mode and is not being asked to provide heating or hot water.
Your boiler's internal water pressure sensor is telling the system that the water flow has stopped or the sensor itself is not detecting any movement, which usually prevents the heating from turning on.
Your boiler is simply indicating that the 'warm start' or cylinder heating feature requested by your thermostat is currently turned off.
This code is not actually an error, but a display setting that shows which external device or auxiliary pump is currently connected to your boiler's secondary circuit.
This code is not actually an error, but a display setting that shows which external device your boiler is currently controlling.
This code is simply an information display showing whether your boiler is set to fill itself automatically, semi-automatically, or requires you to do it manually.
Your boiler is displaying the current operating speed of the fan, which is a normal status message rather than a breakdown.
This code is simply showing you the current speed of your boiler's internal cooling fan and is not a warning of a fault.
Your boiler is currently reporting the status of the valve that switches your water flow between heating your home and heating your hot water tap.
This code is simply showing you a live readout of how much hot water is currently flowing through your boiler and is not an error message.
This code is simply an information display showing the current temperature of the water in your solar heating system, rather than indicating a fault.
This code is not a fault; it is simply showing you the current temperature of the water flowing through your heating system.
Your boiler is simply displaying the current temperature reading of the water returning to it from your radiators; this is an information code rather than a fault.
This code is simply an information display showing the current setting used to manage how much heat your radiators produce based on the outdoor temperature.
Your boiler is displaying a status code rather than a fault, indicating the current internal setting for how hot it should make your radiators based on the outside temperature.
Your boiler is simply displaying the current temperature reading from an external weather sensor connected to your system.
Your boiler is displaying a diagnostic setting for its internal air fan rather than a breakdown error, but it may indicate an issue with the fan's operation or the circuit board settings.
Your boiler is currently recalibrating its internal fan settings and is not reporting a failure; it is performing a routine adjustment rather than displaying an active heating breakdown.
Your boiler is currently checking its settings for solar-heated water to ensure it meets safety standards for preventing bacteria growth.
Your boiler has detected that it is getting too hot and has switched itself off multiple times to prevent damage.
Your boiler has failed to light several times and is currently recording these failed attempts rather than performing an action.
This code is simply an information display showing your boiler's internal setting for how much the temperature automatically drops overnight.
This code is simply an information display showing how long your boiler takes to light the flame on average, rather than an error or a fault with your heating system.
This code is not an error, but rather a status display showing how long the boiler took to light its flame during the last ignition attempt.
This code simply confirms whether your boiler is currently set to keep a small amount of water pre-heated for faster hot water taps, rather than indicating a fault.
Your boiler is currently in a mandatory waiting period, purposely resting to prevent it from cycling on and off too frequently.
Your boiler is struggling to light itself on the first try and is keeping a record of these failed attempts.
Your boiler has failed to light the flame after two attempts and is currently tracking how many times this has happened.
Your boiler is currently monitoring or testing the internal valve that decides whether to send hot water to your radiators or your taps.
Your boiler has stopped working because it cannot communicate with the sensor that monitors the temperature of the water leaving the unit.
Your boiler has stopped working because it cannot accurately measure the temperature of the water leaving the unit due to a sensor or wiring connection fault.
Your boiler has stopped working because it cannot accurately measure the temperature of the water returning to the unit.
Your boiler has stopped working because it cannot accurately measure the temperature of the water returning to the unit due to a faulty sensor or wiring.
Your boiler has detected an electrical fault with the internal sensor that monitors the water temperature leaving the unit, causing it to shut down for safety.
Your boiler has stopped working because it thinks the water returning to the unit is much hotter than it actually is, causing it to shut down for safety.
Your boiler has lost the ability to measure the temperature of your hot water cylinder because of a faulty sensor or a wiring issue, meaning it cannot heat your water correctly.
Your boiler has detected an electrical fault with the sensor that monitors your hot water tank, meaning it cannot accurately tell if your water is hot enough.
Your boiler has switched itself off because it has reached an unsafe temperature and needs to cool down.
Your boiler has stopped working because the water pressure inside the system has dropped too low to operate safely.
Your boiler has shut down because there is a significant difference between the water temperature leaving the boiler and the temperature returning to it, usually caused by a circulation problem.
Your boiler has shut down because the internal water temperature is heating up much faster than it can be circulated away, usually meaning the water is stuck or the pump is struggling.
Your boiler has shut itself down because the air being pushed out of the chimney pipe has become dangerously hot.
Your boiler has sensed a flame when there shouldn't be one, so it has shut down as a safety precaution to prevent damage.
Your boiler is trying to light itself to provide heat, but it is failing to create a flame, likely because it is not getting enough gas or the spark isn't catching.
Your boiler was working but the flame went out and it cannot manage to light itself back up.
Your boiler's fan is unable to spin at the correct speed, which prevents the boiler from safely clearing exhaust fumes and starting the ignition process.
Your boiler is struggling to breathe because it cannot properly detect the flow of air required for safe operation.
Your boiler has lost its ability to communicate with its external controls, such as your thermostat, due to an electrical glitch in the internal data wiring.
Your boiler is unable to correctly control the flow of gas, causing it to shut down for safety purposes.
Your boiler has detected that the gas valve is not closing as quickly as it should, preventing the unit from shutting down the burner safely.
Your boiler's internal computer brain is having trouble reading its memory, causing the system to stop working for safety.
Your boiler has detected an internal communication error between its electrical sensors and the main control board, causing it to shut down for safety.
Your boiler's internal control board has become too hot and has shut down the system to prevent damage.
Your boiler's electronic control board has detected a confusing signal from the flame sensor, causing the system to shut down for safety.
Your boiler is struggling to keep its flame burning steadily, causing it to shut down for safety.
Your boiler’s control board has lost its identity settings, meaning the internal computer no longer knows which specific model it is supposed to be operating.
Your boiler is struggling to accurately measure the water temperature leaving the unit, usually because a sensor has failed or become disconnected.
Your boiler has detected that the sensors measuring water temperature going in and out are giving conflicting readings, so it has shut down as a safety precaution.
Your boiler is struggling to read how much water is in the system because of a sensor issue, which has caused it to stop working for your safety.
Your boiler's internal sensor has detected that the water pressure is too high or the sensor itself is sending an incorrect reading.
Your boiler is unable to sense water moving or pressure building when it tries to start up, which has caused it to shut down for safety.
Your boiler's safety sensor has detected that the main heating component is getting too hot, so the system has shut itself down to prevent damage.
Your boiler is struggling to push waste gases out through the flue or is unable to clear internal condensation water properly.
Your boiler is having trouble communicating with an external hot water control component, meaning it doesn't know the temperature of the water heading to your taps.
Your boiler is firing up, but it doesn't detect the water getting hotter quickly enough, so it has shut down to prevent itself from overheating.
Your boiler is confused because its internal thermometers are giving conflicting readings and don't agree on how hot the water actually is.
Your boiler has stopped working because its internal thermometers are giving conflicting readings and believe they have been fitted to the wrong pipes.
Your boiler has stopped providing heat because a safety limit switch for your underfloor heating has been triggered or disconnected.
Your boiler has detected a problem with the internal ignition components, meaning it cannot safely light the burner to provide heat or hot water.
Your boiler has detected an electrical connection issue with the gas valve, meaning it cannot safely ignite to provide heating or hot water.
Your boiler's main internal pump is not speaking correctly to the control board, preventing the system from circulating heat.
Your boiler has lost the ability to monitor the water temperature in your hot water cylinder due to an electrical connection fault.
Your boiler's internal computer is receiving the wrong information about its own identity, preventing it from running safely.
Your boiler's internal computer has failed a self-test and is no longer able to communicate with the rest of the system.
This code isn't an active fault but rather a menu view showing the history of past errors your boiler has experienced.
Your boiler has stopped working because the water pressure is too low for it to operate safely.
Your boiler's computer brains are not talking to each other correctly because a security code needs to be re-entered after a repair.
Your boiler is currently running an automatic program to remove trapped air from the system, which usually happens during startup or after maintenance.
Your boiler is currently running a self-cleaning routine to remove trapped air bubbles from the system.
Your boiler has failed while running a specific test used for commissioning or high-power performance checks.
Your boiler is simply running a routine internal test to check it can operate at its maximum power level after starting up.
Your boiler is not in a fault state; it is simply running a pre-programmed test to check how it performs at its lowest power setting.
Your boiler is currently running a background self-test to check it can operate safely at its lowest power setting.
Your boiler is undergoing a temporary calibration process where it checks its heating settings; it is not a fault, but a normal status message.
Your boiler is currently running a safety program to remove trapped air from the internal pipes and heat exchanger.
Your boiler is running a specialized internal test to ensure its safety sensor correctly shuts the system down if it gets too hot.
Your boiler is currently running a self-check program to fill the heating system with water and is not experiencing a permanent fault.
Your boiler is currently running a self-diagnostic test to check the water pressure and fill level as it prepares to start up.
Your boiler is currently running a self-cleaning mode to remove trapped air bubbles from the pipes and pump.
Your boiler is simply letting you know that it is currently busy heating up water for your taps or shower.
Your boiler is simply preparing its internal airflow to heat your water, which is a normal part of its startup process and not an error at all.
Your boiler is currently just starting the process to heat your water, so it is working normally and does not have a fault.
Your boiler is simply performing a routine cooling-down process after you last used hot water, and there is no fault with your system.
Your boiler is currently cooling down its internal components after you have finished using hot water, which is a normal part of its shutdown process.
Your boiler is simply finishing its cooling cycle after you have finished using hot water, and no action is required.
Your boiler is currently performing a safety check on its internal airflow system and is waiting for a pressure sensor to confirm it is safe to ignite.
Your boiler is currently performing an internal health check on its sensors and has temporarily paused heating and hot water to ensure everything is functioning safely.
Your boiler is struggling to switch between providing hot water and heating your radiators because an internal valve is stuck or malfunctioning.
Your boiler's fan is struggling to start or run at the correct speed, which is preventing the boiler from firing up for safety.
Your boiler is struggling to move heated water to your hot water cylinder, which means you may not have any hot water.
Your boiler's internal pump is having trouble moving water through the system, which is preventing it from providing heating or hot water.
Your boiler is struggling to push water around your radiators because an external pump is not working as expected.
Your boiler is currently completing a routine check of its burner system while it is in the process of starting up.
Not faults — these are normal operating states. Tap to expand.
BoilerFaultCodes