96 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Replaced by: NCB500
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Your boiler is struggling to detect the current outdoor temperature, which means it cannot automatically adjust your heating performance to match the weather.
Your boiler is struggling to accurately read its own internal water temperature, so it has stopped operating to prevent the system from getting too hot.
Your boiler is struggling to accurately measure the temperature of the water currently being used to heat your home.
Your boiler is having difficulty reading the temperature of the water flowing through your heating system, which means it cannot safely heat your home or water.
Your boiler has lost the ability to accurately measure the temperature of the water returning to it, which causes it to shut down for safety reasons.
Your boiler is struggling to accurately detect the temperature of the hot water it is attempting to supply to your taps.
Your boiler is having trouble accurately reading the temperature of the hot water it is attempting to supply to your taps.
Your boiler is struggling to register that you have turned on a hot tap, meaning it won't fire up to heat the water for your shower or kitchen faucet.
Your boiler is struggling to detect the temperature in your home because the wall-mounted sensor in your living area has lost communication or developed a fault.
Your boiler is having trouble reading the temperature in the second heating zone controlled by an external wall sensor.
Your boiler is struggling to read the temperature inside your room correctly because a sensor has developed a fault.
Your boiler is struggling to accurately measure how much water is inside the system, which is preventing it from firing up safely.
Your boiler is struggling to accurately read how much water is inside its system, so it has safely shut down to prevent any internal damage.
Your boiler's internal communication system has developed a short circuit, preventing the control board from sending signals to the rest of the unit.
Your boiler's internal communication system has experienced a short circuit, causing the control board to lose contact with essential internal components.
Your boiler's internal communication system is confused because two or more parts are trying to use the same digital identification signal.
Your boiler is having trouble 'talking' to its wireless thermostat, meaning it cannot receive signals to turn the heating or hot water on.
Your boiler's computer has lost its internal settings, meaning it cannot remember how to operate correctly and requires a professional to reset or replace the main control board.
Your boiler’s internal control system has detected a software or communication error and has safely shut down to prevent further issues.
Your boiler's computer system has detected a minor internal processing error that is preventing it from operating correctly.
Your boiler has detected a minor internal software error and has automatically reset itself to try and clear the issue.
Your boiler's computer system has encountered an internal processing error, meaning it cannot safely operate or control your heating and hot water.
Your boiler is having trouble communicating with an internal control board responsible for managing extra heating system features, which may prevent your heating or hot water from working correctly.
Your boiler's internal computer is detecting a communication conflict because two separate controllers are trying to manage the system at the same time.
Your boiler has lost its internal time settings, which usually happens after a power cut or if a tiny backup battery inside the controller has run flat.
Your boiler is struggling to breathe because its air intake filter is blocked by dust or debris, preventing it from working correctly.
Your boiler has detected that the temperature of the exhaust fumes coming out of the flue is too high, so it has safely shut itself down to prevent overheating.
Your boiler has detected that the exhaust gases are not escaping properly, so it has safely shut itself down to prevent carbon monoxide buildup.
Your boiler has detected that the water pressure inside the system has risen too high, causing it to shut down for safety.
Your boiler has stopped working because the amount of water circulating inside the system has dropped below the required level.
Your boiler is struggling to reach the temperature it needs to provide heating and hot water to your home.
Your boiler's secondary heating zone is failing to reach the required temperature, likely because the system is struggling to circulate heat to a specific part of your home.
Your boiler has failed to complete its routine high-temperature cycle designed to prevent bacteria in your hot water tank, likely because the water is not getting hot enough.
Your boiler has detected that water is failing to drain away properly, so it has stopped working to prevent internal flooding.
Your boiler has encountered an internal communication error where the main control board is unable to identify or process a specific fault signal.
Your boiler is struggling to accurately measure its own internal temperature due to a faulty sensor, which has caused it to shut down for safety reasons.
Your boiler has detected an issue with a temperature sensor in your heating system, which may prevent your radiators from heating up correctly.
Your boiler's main control computer is failing to start up properly, meaning the system is currently unable to operate safely or effectively.
Your boiler is struggling to ensure the air and gas mixture is correct for safe operation and has temporarily locked out to prevent any risk.
Your boiler is having trouble controlling the gas flow needed to heat your water, which means the unit has shut down as a safety precaution.
Your boiler is not detecting enough air flow to safely release exhaust gases, so it has shut itself down to prevent a hazard.
Your boiler's computer is having trouble communicating with the sensor that monitors your water pressure, meaning it cannot safely confirm everything is operating as it should.
Your boiler has detected that water is not circulating properly through your heating system, so it has safely shut down to prevent overheating.
Your boiler is failing to detect any water flowing through the hot water system, meaning it will not switch on to heat your taps or shower.
Your boiler has detected that an internal component is overheating and has shut itself down to prevent any damage or safety issues.
Your boiler has detected that a seal protecting the internal electronics has become dangerously hot and has shut itself down to prevent damage.
Your boiler has detected an issue with the air supply or exhaust venting system, preventing it from safely clearing waste gases.
Your boiler has detected an dangerously high temperature inside its internal engine system and has switched itself off to prevent permanent damage.
Your boiler's internal engine is failing to reach the necessary operating heat during startup, so it has stopped working to prevent potential damage.
Your boiler has detected an internal cooling system issue and has automatically shut down to prevent damage from overheating.
Your boiler has detected an internal cooling system issue and has shut down to prevent potential overheating or mechanical damage.
Your boiler has detected an electrical problem or overheating issue near its internal safety seals, causing it to shut down to prevent damage.
Your boiler has detected an internal cooling issue and has automatically shut down to prevent damage to its electrical components.
Your boiler has detected dangerously high temperatures inside its cooling system and has shut down to prevent permanent damage or a fire hazard.
Your boiler has detected what looks like a flame inside when it should be turned off, which causes it to shut down for safety reasons.
Your boiler has detected that a critical internal part is not warming up as expected, so it has shut down to protect itself from damage.
Your boiler has detected a significant temperature mismatch between its internal sensors, which means it has safely shut itself down to prevent potential overheating.
Your boiler's internal management system has detected a critical communication error with the main brain of the unit, causing it to shut down for safety reasons.
Your boiler's internal computer is unable to verify the connection to a key component, causing the system to stop working as a precaution.
Your boiler has lost its connection to the energy grid while trying to operate independently, causing the system to shut down for safety.
Your boiler has detected an internal electrical connection failure that is preventing it from operating safely, which means it will stay locked out until a professional inspects the internal circuitry.
Your boiler is failing to heat up as quickly as it expects to when it first starts, which is preventing it from safely operating.
Your boiler has detected that the flue pipe attached to the unit is not pushed in securely enough, causing it to block the system's safety sensors.
Your boiler has detected that it is getting too hot inside, so it has safely shut itself down to prevent any damage.
Your boiler is trying to start up but is failing to light the flame, which means your heating and hot water have stopped working.
Your boiler has detected a flame when it should be switched off, which has caused it to shut down for safety reasons.
Your boiler has detected that the burner flame has gone out unexpectedly, so it has safely shut down to prevent unburnt gas from building up.
Your boiler has detected that it is getting dangerously hot and has shut itself down to prevent any internal damage.
Your boiler is overheating because the exhaust gases are hotter than they should be, so it has safely shut itself down to prevent damage.
Your boiler has detected that it is running much hotter than it should be and has shut down to prevent damage to itself.
Your boiler has sensed that the internal water temperature is dangerously high and has automatically shut itself down to prevent damage.
Your boiler has detected that the temperature of the exhaust gases leaving the unit is higher than it should be, so it has shut down to prevent any damage.
Your boiler is struggling to correctly mix the air and gas needed for combustion, which prevents it from firing up safely.
Your boiler's air circulation system is not spinning correctly, which is preventing it from safely removing exhaust gases and heating your home.
Your boiler is struggling to breathe properly because it cannot push out exhaust gases or pull in fresh air as it should.
Your boiler has detected an inaccurate temperature reading from the sensor that monitors the water heading to your radiators, causing it to shut down to prevent overheating.
Your boiler has lost the ability to accurately measure the temperature of the water returning to it, so it has safely shut down to prevent overheating.
Your boiler is struggling to accurately read the temperature of the water being sent to your radiators, causing it to stop working for your own protection.
Your boiler is struggling to accurately read the temperature of the water coming back into it, which is preventing it from heating your home properly.
Your boiler has detected that hot and cold water pipes are likely connected the wrong way around or the internal sensors are misreading the water flow direction.
Your boiler has detected that the water pressure inside the system is too low to run safely, so it has turned itself off.
Your boiler has detected that the water pressure inside the heating system is too high for it to operate safely.
Your boiler is struggling to detect the water pressure inside the system because the sensor that monitors it is malfunctioning or providing incorrect readings.
Your boiler is struggling to accurately read the temperature of the water inside the storage tank, which means it cannot heat your water reliably.
Your boiler's internal computer is experiencing a communication or hardware error, which has caused it to shut down to prevent further damage.
Your boiler's internal computer is confused because its physical configuration switches have been moved or incorrectly set, preventing it from starting safely.
Your boiler's computer memory has encountered a data error, which is preventing the system from starting up or operating correctly.
Your boiler's computer is experiencing a internal electronic glitch that is preventing it from starting up correctly.
Your boiler is struggling to talk to other units in your heating system, likely due to a loose wire or a connection issue between them.
Your boiler is struggling to detect the temperature outside, which may cause it to run less efficiently than usual.
Your boiler has detected that the flue pipe, which carries exhaust gases outside, is not pushed in securely enough to ensure it is safe to operate.
Your boiler has detected that the water level inside the heating system is too low to run safely, so it has shut itself down to prevent damage.
Your boiler's main control system is having trouble talking to its display panel, which is preventing the unit from starting correctly.
Your boiler has lost the connection to the system that tells it which parts of your home need heating, causing the unit to stop operating correctly.
The boiler is detecting that its front cover is not closed or sealed correctly, which is a safety feature to prevent fumes from leaking into your home.
Your boiler has detected an issue with the way it is managing its gas supply, meaning it has safely shut itself down to prevent it from operating incorrectly.
BoilerFaultCodes