70 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
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Your boiler has detected that it is running too hot and has automatically shut itself down to prevent damage.
Your boiler has stopped working because the water pressure inside your heating system has dropped too low to operate safely.
Your boiler has detected that the water pressure in your heating system is currently set too high for safe operation.
Your boiler has detected a fault with the sensor responsible for measuring the temperature of your hot water, so it has shut down to prevent incorrect operation.
Your boiler has stopped working because it is unable to accurately measure the temperature of the water being sent to your radiators.
Your boiler has detected a safety-related issue and has automatically shut itself down to prevent damage or dangerous operation.
Your boiler has detected that the water pressure inside the system is too low to operate safely.
Your boiler has failed to ignite or stay lit because it cannot detect a flame, so it has safely shut down to prevent gas from escaping.
Your boiler is struggling to push water around your heating system, which is often caused by trapped air, a blockage, or a pump that has stopped working.
Your boiler has detected an issue with a secondary sensor that monitors the temperature of the water or heating circuit, causing it to stop operating to stay safe.
Your boiler has detected an issue with the sensors that monitor the safety and flow of exhaust gases, so it has shut itself down to prevent any risk.
Your boiler has detected an issue with the sensor that monitors the air and fumes inside the unit, meaning it has safely shut itself down to prevent any risk.
Your boiler has detected an issue with the internal ventilation system that removes exhaust gases, and as a safety precaution, it has stopped running to prevent unsafe operation.
Your boiler has detected that the water temperature in one of your heating circuits has become dangerously high and has automatically shut down to prevent damage.
Your boiler has lost the signal from a sensor responsible for monitoring the temperature in your underfloor or radiator heating zones, which may stop those specific rooms from heating up correctly.
Your boiler has detected that the water temperature in your secondary heating circuit has become too hot, causing it to shut down for safety.
Your boiler is having trouble communicating with the secondary heating circuit that controls a specific part of your home, such as an underfloor heating zone.
Your boiler's solar water heating system is unable to read the temperature from the roof panel, meaning the solar energy collection feature is currently disabled.
Your boiler is having trouble communicating with the temperature sensor linked to your solar water heating system, which may prevent the boiler from correctly using solar energy to heat your water.
Your boiler is having trouble communicating with the temperature sensor connected to your solar water heating system, which may prevent the solar panels from working correctly.
Your boiler's electronic control system is incorrectly set up to communicate with solar thermal panels that are not currently part of your heating arrangement.
Your boiler is displaying a communication error because it is struggling to recognise an internal setting or a connected external control accessory.
Your boiler's internal electronic system is failing to communicate correctly between its control modules, meaning the unit cannot safely start.
Your boiler has shut down because it detected that exhaust gases are not being cleared away safely through the flue.
Your boiler has stopped working because the water pressure inside the system has dropped too low and needs topping up.
Your boiler has detected that there is too much water pressure in the system, which has caused it to shut down for safety.
Your boiler has detected a problem with the sensor that monitors hot water temperature, which may lead to no hot water or inconsistent temperatures.
Your boiler has detected a problem with the internal temperature sensor that monitors water leaving the unit, preventing it from heating your home safely.
Your boiler is failing to light the flame properly, meaning it cannot heat your home or water.
Your boiler has likely overheated, causing a safety sensor to shut it down to prevent damage.
Your boiler is struggling to detect the flame it needs to stay lit, which prevents it from heating your home or water.
Your boiler is not moving water through the pipes correctly, which causes it to shut down to prevent overheating.
Your boiler has detected an error with an internal temperature sensor or a setting mismatch, meaning it cannot accurately monitor the water temperature.
Your boiler has detected a communication problem with the part that controls the gas flow, meaning it cannot safely light or manage the flame.
Your boiler's computer has been set to the wrong internal configuration mode and cannot operate safely until the settings are corrected.
Your boiler has detected that the exhaust gases are too hot or the sensor monitoring them has failed, causing the system to shut down for safety.
Your boiler has detected an issue with the sensor that monitors exhaust fumes, causing the system to shut down for safety.
Your boiler has stopped working because it cannot communicate with the fan that clears away waste gases.
Your boiler has detected that its two internal temperature sensors are giving very different readings, causing it to shut down for safety.
Your boiler has stopped working because the waste water pipe is backed up or blocked, preventing the unit from draining safely.
Your boiler has been manually reset too many times in a short period and has temporarily locked itself for safety.
Your boiler has detected a problem with the internal sensor that measures the temperature of the water returning from your radiators, preventing it from operating correctly.
Your boiler has stopped working because the electricity supply coming into your home has dropped to an unusually low and unsafe voltage.
Your boiler's safety system has detected a potential blockage or problem with the way it releases exhaust gases, causing the unit to shut down for safety.
Your boiler has detected an issue with the electrical power coming into your home and has shut down for safety.
Your boiler has failed to light several times in a row and has locked itself out for safety.
Your boiler has detected that one of the control buttons is stuck or the main control board is malfunctioning, preventing you from choosing settings.
Your boiler is having trouble communicating with your external thermostat or wall controller, which may prevent your heating from turning on.
Your boiler is failing to light because the internal computer and the gas valve are not communicating correctly to create a flame.
Your boiler has switched itself off because the temperature difference between the water leaving and returning is too high, which usually means the water isn't flowing through the system correctly.
Your boiler has detected an inconsistency with its temperature sensors and needs to run a self-test to recalibrate how it monitors heat flow.
Your boiler has detected that a temperature sensor is not sitting correctly on the main pipe, meaning it cannot accurately monitor the water temperature.
Your boiler has detected a problem with one of its internal temperature sensors, meaning it cannot accurately monitor the heat being sent to your radiators.
Your boiler has detected an electrical fault with the gas valve control system, preventing it from managing the fuel supply safely.
Your boiler has detected an electrical issue with the gas control valve, preventing it from safely regulating the fuel needed for the flame.
Your boiler has detected an internal communication or electronic issue with the gas control valve, preventing it from safely regulating the fuel supply.
Your boiler has detected an internal communication failure between the control board and the gas valve, meaning it cannot safely manage the fuel flow to stay alight.
Your boiler has detected an ignition issue caused by a potential blockage in the air or exhaust pipes, preventing it from starting safely.
Your boiler has shut down because it has failed to ignite or maintain a flame several times in a row.
Your boiler is struggling to burn gas correctly and may restart itself, but it could lead to a full lockout if the issue persists.
Your boiler has detected that the gas supply pressure is too low to operate safely and effectively.
Your boiler's internal computer has detected a technical fault with its own circuitry and has shut down to protect itself.
Your boiler is struggling to maintain a consistent flame, which is likely caused by a dirty sensor or an issue with the air and gas mixture.
Your boiler is struggling to burn gas correctly and has shut down for safety because it cannot reach the required power level to operate.
Your boiler is struggling to get the right mix of air and gas for the flame, which has caused the system to stop working for safety.
Your boiler is struggling to burn gas correctly and efficiently, which is preventing it from running at the power level it needs to heat your home.
Your boiler is struggling to maintain a steady flame and is shutting down because it thinks the fire has gone out unexpectedly.
Your boiler has shut down because it cannot safely expel exhaust fumes out of the external flue pipe.
Your boiler's computer brain has encountered a glitch while trying to start up and cannot proceed.
Your boiler's main internal computer brain has developed a critical fault and is no longer communicating with the rest of the system.
Not faults — these are normal operating states. Tap to expand.
BoilerFaultCodes