151 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
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This boiler uses LED flash patterns
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Your boiler has stopped working because of a communication error between its internal sensors and the main control board.
Your boiler has been left in a manual testing mode after a service, which is preventing it from running at normal power.
Your boiler has been left in a manual testing mode, usually used by engineers during a service, and needs to be returned to its normal setting.
Your boiler's internal computer parts do not recognise each other and are failing to communicate correctly.
Your boiler’s internal computer chip is incompatible with its main circuit board, meaning the internal parts are not communicating correctly.
Your boiler's internal computer has lost communication with a specific configuration chip, meaning the unit no longer knows its own settings and cannot operate.
Your boiler is working correctly and is simply informing you that it is currently heating your radiators.
Your boiler is operating normally and is currently providing heat to your radiators.
Your boiler is simply notifying you that it is currently busy heating up water for your taps or shower.
Your boiler is simply indicating that it is currently busy heating up the tap water for your home.
Your boiler is working normally and is simply waiting for the thermostat to tell it to start heating.
Your boiler is taking a short rest to prevent it from switching on and off too frequently, which helps protect its internal parts.
Your boiler is simply resting because it has reached the required temperature or there is no current demand for heating or hot water.
Your boiler is working correctly and is simply waiting for you to turn up your thermostat or turn on a hot tap.
Your boiler is temporarily pausing because it has already reached the required heat and is waiting for the water temperature to drop before firing up again.
Your boiler has stopped heating because the water inside it has become hotter than it is supposed to be.
Your boiler is currently running at full power for a manual testing procedure and won't respond to your normal thermostat settings.
Your boiler is currently stuck in a professional testing mode used by engineers to check emissions, which prevents it from operating normally for heating and hot water.
Your boiler is overheating because the water inside it is getting too hot too quickly, causing the system to shut down for safety.
Your boiler has switched itself off because it has detected an overheat situation, likely caused by the system water pressure being too low.
Your boiler has recorded that a technician's diagnostic tool was plugged into its internal memory, usually during a previous service or repair.
Your boiler is attempting to start but cannot detect a flame, causing the system to shut down for safety.
Your boiler thinks it can see a flame even though the burner isn't actually lit, which is preventing it from starting up safely.
Your boiler's internal computer chips are unable to communicate with each other because their software versions do not match.
Your boiler has started up but is not detecting the expected heat increase, which often means the water isn't moving correctly or a sensor is failing.
Your boiler is temporarily reducing its power and taking a short break because it has reached its target temperature too quickly.
Your boiler is currently running a self-diagnostic check of its internal parts, which usually happens during a startup or reset sequence.
Your boiler is working correctly and is simply increasing its power to reach the required temperature, which is normal operation and not a fault.
Your boiler is currently going through its normal startup sequence and is getting ready to light the flame.
Your boiler has stopped working because it has detected an electrical issue or a mismatch with the gas control valve's internal settings.
Your boiler is staying in hot water mode even when you aren't using a tap, which is preventing your central heating from turning on.
Your boiler is temporarily pausing the hot water production to prevent itself from overheating or cycling too frequently.
Your boiler is still detecting a flame even after it has been told to shut off the gas, which is a safety concern that prevents the unit from operating.
Your boiler has detected an unstable electrical supply or an internal fault with its electronic control board.
Your boiler is not receiving a stable or strong enough supply of electricity to operate safely and has shut down as a result.
Your boiler's internal computer brain is reporting a compatibility error, meaning it doesn't recognize the plug-in electronic chip that controls its heating functions.
Your boiler's internal computer chip is giving the wrong signal to the main control board, which has caused the system to stop working.
Your boiler's internal temperature sensors are reporting conflicting information or a broken connection, which is preventing the system from heating correctly.
Your boiler has lost its digital connection to its internal controls or external thermostat, meaning it cannot receive the instructions it needs to operate.
Your boiler has detected that the water pressure is too low for it to heat your home safely and needs to be topped up.
Your boiler's hot water sensor is not reporting correctly, which means the system cannot safely heat your water to the right temperature.
Your boiler is struggling to monitor the temperature of your hot water because a internal sensor has likely failed or become disconnected.
Your boiler has lost connection to its outdoor thermometer, meaning it cannot automatically adjust your heating based on the weather outside.
Your boiler's internal computer has lost communication with the sensor that monitors water pressure, meaning it cannot safely tell if there is enough water in the system to operate.
Your boiler has lost connection with its outdoor thermometer, meaning it might struggle to adjust the heat level correctly based on the weather.
Your boiler has stopped working because its internal thermometer has detected an electrical fault and can no longer monitor the water temperature accurately.
Your boiler has lost communication with the internal thermometer that monitors water temperature, causing the system to shut down as a safety precaution.
Your boiler has stopped working because an internal temperature sensor has malfunctioned and is sending an incorrect signal to the main control board.
Your boiler has lost its connection to the sensor that monitors internal heat levels, meaning it has shut down as a safety precaution.
Your boiler has stopped working because it cannot confirm that a flame is safely burning inside the unit.
Your boiler has stopped working because its main control board cannot communicate with the gas valve, preventing it from heating your water.
Your boiler has stopped working because the internal control board is not receiving the correct signal from the valve that controls the gas flow.
Your boiler has unexpectedly lost its flame while it was running, meaning it can no longer provide heat or hot water.
Your boiler's computer memory chip is faulty or incorrectly installed, preventing the system from starting up.
Your boiler is struggling to keep its flame lit during operation, meaning your heating and hot water might cut out or fail to start.
Your boiler is struggling to keep its flame lit during start-up and requires a professional service and calibration to run safely.
Your boiler has detected that a internal sensor is sending an unusual signal, likely due to a loose wire or a faulty electronic part, which has caused the system to stop working.
Your boiler has sensed that water is not moving through the system fast enough, causing it to shut down to prevent overheating.
Your boiler has detected that the water inside it is getting too hot and has shut down as a safety precaution.
Your boiler is heating up too quickly because the water inside isn't moving fast enough to carry the heat away.
Your boiler has detected that the water is heating up too quickly or unevenly, causing it to shut down to prevent overheating.
Your boiler has detected that the water pressure in your heating system is falling much too quickly, which usually means there is a significant leak or a fault with how the system handles pressure.
Your boiler has detected that the water pressure in your heating system is too low to operate safely.
Your boiler has detected that there is not enough water circulating through the system, which can happen if there is a leak or if the internal pump has become stuck.
Your boiler's internal pump is unable to move water around the system, likely because it is jammed or there is too much air trapped inside it.
Your boiler has detected an electrical fault with the sensor that measures the temperature of exhaust gases, causing the system to shut down for safety.
Your boiler has lost its ability to accurately measure the temperature of the water going to your taps, meaning you may only have cold water or inconsistent temperatures.
Your boiler has lost its connection to the external heating controls or room thermostat, meaning it cannot receive the signal to turn on.
Your boiler is struggling because it isn't receiving a steady or correct amount of electricity to power its internal computer.
Your boiler has lost its internal identity chip, meaning it no longer knows its specific model settings and cannot operate.
Your boiler's internal computer has encountered a critical error and can no longer communicate with the rest of the system.
Your boiler has detected that the fan or the air circulation system has stopped working while it was running, causing it to shut down for safety.
Your boiler's main internal computer has developed a serious electronic fault and can no longer control the heating process safely.
Your boiler's fan or air pressure sensor has detected air movement when it should be off, often caused by strong winds or a technical glitch.
Your boiler has detected that the internal fan responsible for clearing exhaust fumes is not spinning fast enough, so it has shut down for safety.
Your boiler has switched itself off because the internal fan is spinning at the wrong speed, meaning it can't safely clear away waste gases.
Your boiler has stopped working because the fan that helps remove waste gases is not spinning fast enough to operate safely.
Your boiler has detected that the internal fan, which safely clears exhaust gases, isn't spinning, so it has shut down as a safety precaution.
Your boiler has stopped working because the fan that clears exhaust gases is not spinning fast enough to operate safely.
Your boiler has shut down because the internal fan that moves air through the system has unexpectedly stopped spinning while it was running.
Your boiler is having trouble communicating with the optional weather sensor located outside your home.
Your boiler has stopped working because the water level inside the system has dropped too low to run safely.
Your boiler has stopped working because the internal pump is not moving water through the system as it should.
Your boiler has detected a problem with the sensor that monitors water returning to the unit, meaning it cannot safely regulate the temperature.
Your boiler has stopped working because it has lost its connection to the internal sensor that monitors the temperature of the water returning to the unit.
An external safety device or thermostat has stopped the boiler from running to prevent potential damage, such as a leak or overheating.
Your boiler has detected that the water inside is heating up too quickly, which usually means the water isn't circulating properly and triggered a safety shut-off.
Your boiler has detected that the water is heating up too quickly or isn't moving through the system properly, causing it to shut down to prevent overheating.
Your boiler has shut down because it thinks the water returning to the unit is dangerously hot, which usually means water is not flowing through the system correctly.
Your boiler is overheating because the water inside it is getting too hot too quickly, causing the system to shut down for safety.
Your boiler's internal thermometer that monitors the water temperature for your heating is broken or has a loose connection, causing the system to shut down for safety.
Your boiler has detected an electrical fault with the internal sensor that monitors water temperature, meaning it cannot safely heat your water.
Your boiler has lost connection with the sensor that measures water temperature, causing it to stop heating for safety.
Your boiler has stopped working because it can no longer measure the temperature of the water leaving the unit, usually due to a loose wire or a faulty internal sensor.
Your boiler has detected an electrical fault with the internal sensor that monitors water temperature, causing the system to shut down for safety.
Your boiler has lost its connection to the sensor that monitors water temperature, causing the system to shut down as a safety precaution.
Your boiler has sensed that the water inside it has become too hot and has shut down as a safety precaution.
Your boiler has overheated because the water inside is getting too hot or is not flowing correctly, causing the system to shut down for safety.
Your boiler has shut down because it detected that the exhaust gases are getting too hot or the internal safety sensor has failed.
Your boiler has sensed that it is becoming dangerously hot and has shut itself down to prevent damage or overheating.
Your boiler has switched itself off to prevent damage because it has detected that it is getting dangerously hot or a safety sensor has failed.
Your boiler has become too hot and has shut itself down as a safety precaution to prevent internal damage.
Your boiler has reached an unsafe temperature and has shut itself down to prevent damage.
Your boiler has sensed that the water inside is getting too hot and has shut itself down for safety.
Your boiler has shut down because internal components have become dangerously hot, likely due to a lack of water circulation or a component failure.
Your boiler has shut down because a safety sensor has detected that the exhaust gases are getting too hot or the sensor itself has lost its electrical connection.
Your boiler is failing to light the flame needed to heat your water and radiators, which often happens when the gas supply is interrupted or a component is worn out.
Your boiler has stopped working because it cannot light the gas or keep the flame burning to provide heat.
Your boiler has lost its flame while it was running, which means it has safely shut down because it can no longer detect the fire needed to heat your water.
Your boiler has lost its connection to the gas valve, meaning it cannot light the flame to provide heat or hot water.
Your boiler's internal computer brain is having trouble communicating with the heating system and needs a restart to try and clear the error.
Your boiler is trying to light the gas but can't sustain a flame, so it has locked itself for safety after too many attempts.
Your boiler's internal computer has encountered a software or communication error and cannot safely operate the burner.
Your boiler has slowed down because it is struggling to circulate water quickly enough through the system, often caused by a blockage or a pump issue.
Your boiler's main internal computer has developed a fault and can no longer control the heating process safely.
Your boiler has encountered an internal electronic communication failure, meaning the control board cannot talk to the parts that start the burner.
Your boiler's computer system has encountered a communication error, meaning it has essentially 'frozen' and cannot talk to its internal components.
Your boiler has detected an internal electrical communication problem between the main control board and the gas valve, preventing it from lighting safely.
Your boiler's internal computer has developed a fault and can no longer communicate with the heating system, causing the unit to shut down for safety.
Your boiler’s internal computer has developed a fault and can no longer communicate with the main control system, preventing the boiler from heating.
Your boiler's main internal computer has developed a fault and can no longer communicate with the rest of the system.
Your boiler’s internal computer has developed a fault and can no longer communicate with its main control board.
Your boiler’s internal computer has developed a serious fault or has disconnected, meaning the system cannot safely tell the boiler when to start or stop.
Your boiler's control system has detected a communication issue with its internal sensors, preventing it from heating your home or water.
Your boiler's computer system has detected an internal electronic failure, meaning it cannot safely control the burner to provide heat or hot water.
Your boiler's internal computer has developed a fault or is not communicating correctly, meaning the system cannot safely operate.
Your boiler's internal computer has developed a serious communication error or a hardware fault, preventing the system from starting safely.
Your boiler's internal computer has encountered a critical communication error and cannot operate safely.
Your boiler's internal computer has developed a fault and can no longer communicate with the heating system, causing the boiler to shut down.
Your boiler's main internal computer has developed a communication error or electrical fault and can no longer control the heating process.
Your boiler thinks it still sees a flame after it has been told to turn off, which is causing it to shut down for safety.
Your boiler thinks there is a flame present when there shouldn't be, which is causing it to shut down for safety.
Your boiler has experienced a temporary interruption in its electrical supply and has stopped working as a safety precaution.
Your boiler thinks it still sees a flame even though the gas should be turned off, which is a safety conflict that requires a professional inspection.
Your boiler thinks it still sees a flame even though it has commanded the gas to turn off.
Your boiler has detected a potential internal gas leak or a serious fault with the gas control valve, causing it to shut down for safety.
Your boiler has detected a potential internal gas leak within its own components and has shut down as a safety precaution.
Your boiler is simply in a temporary 'standby' mode because the reset button was held down too long or pressed by mistake.
Your boiler has lost its connection to the main electricity supply or has experienced a sudden power interruption.
Your boiler's water pressure has dropped too low, which is preventing it from providing full heating and hot water.
Your boiler is experiencing a critical electronic failure that causes it to shut down and try to restart repeatedly.
Your boiler is currently idle because it hasn't been told to turn on by your thermostat or timer.
Your boiler is operating normally and is currently heating your radiators as requested by your thermostat.
Your boiler is overheating because water isn't moving through the system quickly enough to be cooled down.
Your boiler has lost power completely and will not turn on, meaning you have no heating or hot water.
Your boiler is currently resetting itself, which usually happens after a fault has been detected or while it's trying to restart.
Your boiler is currently performing a routine check to see if the spark that starts the flame is working correctly.
Your boiler is having trouble starting up because it cannot confirm that the internal fan is spinning at the correct speed to safely clear waste gases.
Your boiler is struggling to circulate water because the internal pump is not behaving as expected during its startup test.
Your boiler is struggling to switch properly between your heating and hot water, meaning you might lose one or both services.
Your boiler's electronic control board has detected an internal failure in its safety testing system, meaning it cannot verify if the flame is burning safely.
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