64 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
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Your boiler's internal computer screen and main control board are having trouble talking to each other, meaning the unit cannot function.
Your boiler is struggling to push hot water around your radiators because an external pump is not responding correctly.
Your boiler has lost its connection to the sensor that monitors the temperature of the water leaving the unit, causing it to stop running as a safety precaution.
Your boiler has stopped working because one of its internal temperature sensors has lost connection or failed.
Your boiler has stopped working because one of its internal sensors has developed an electrical fault and can no longer measure the temperature of the water leaving the unit.
Your boiler has detected an electrical fault with the sensor that monitors water returning from your radiators, causing the system to shut down for safety.
Your boiler has detected an electrical fault with the sensor that monitors your hot water tank temperature, preventing it from heating your water correctly.
Your boiler has switched itself off because it has detected that the water inside is getting too hot.
Your boiler has stopped working because the water pressure is too low for it to run safely.
Your boiler is struggling to move water around the system properly, causing it to overheat and shut down for safety.
Your boiler is heating up too quickly because water isn't flowing through the system properly, causing it to shut down to prevent overheating.
Your boiler has detected an electrical connection issue or a sudden temperature rise, causing it to shut down for safety.
Your boiler's safety system is detecting a flame when there shouldn't be one, or the sensor that monitors the flame has developed a fault.
Your boiler is not receiving gas or is unable to light a flame to provide heating and hot water.
Your boiler has lost its flame while running and is now unable to relight itself to provide heat or hot water.
Your boiler has detected an issue with the air fan, meaning it cannot safely circulate the air and gas needed to stay lit.
Your boiler has lost communication with its external controls, such as your thermostat, often due to an electrical wiring error or interference.
Your boiler has detected an electrical communication problem with the gas valve, which is preventing it from lighting safely.
Your boiler has detected a potential safety issue where the gas valve is not closing properly or the control board is misreading the gas flow.
Your boiler's internal computer brain has developed a memory error and can no longer process the information it needs to run safely.
Your boiler has detected an electrical fault or a sensor failure and has shut down as a safety precaution.
Your boiler’s internal computer has overheated, causing it to shut down to prevent permanent damage.
Your boiler's internal computer has detected an electrical fault with the flame sensor and has shut down for safety.
Your boiler's internal computer parts have lost their identity settings or been replaced incorrectly, meaning the system can no longer communicate with itself to operate.
Your boiler has detected that a temperature sensor is stuck or faulty, meaning it cannot accurately monitor the water temperature to operate safely.
Your boiler’s temperature sensors are giving conflicting readings, causing the system to shut down to prevent overheating.
Your boiler has lost the ability to monitor its own water pressure due to a sensor or wiring fault, causing the system to shut down for safety.
Your boiler is struggling to read its internal water pressure correctly because of a technical glitch in the sensor or its wiring.
Your boiler is unable to detect a change in water pressure when the pump starts up, preventing it from firing up for heating or hot water.
Your boiler has shut down because a safety sensor has detected that the main heating component is getting too hot or has a broken internal fuse.
Your boiler has shut down because it is unable to drain away the waste water it produces, or a safety sensor on the flue system has been triggered.
Your boiler is confused because it is trying to communicate with an external control box that isn't compatible with its current setup.
Your boiler's computer parts are not communicating correctly because they haven't been told which specific model of boiler they are installed in.
Your boiler is currently running a brief automatic maintenance cycle to remove trapped air from its internal system.
Your boiler is currently running a self-diagnostic test at maximum power to ensure everything is working correctly after ignition.
Your boiler is currently running a brief internal test to check its ignition settings and minimum gas flow, which usually happens during startup or after maintenance.
Your boiler is currently initiating its start-up sequence and is temporarily pausing to check that the pump is moving water correctly before firing the burner.
Your boiler is currently initiating a warm-up sequence and is waiting for the heating system to reach a specific operating temperature before it proceeds.
Your boiler is currently running a mandatory internal safety test to ensure it can shut down correctly if it gets too hot.
Your boiler is currently running an automated self-test to ensure the internal water flow mechanism is in the correct position for system adjustment.
Your boiler is currently moving water around the system correctly, so this is just a normal operational message rather than a fault.
Your boiler is currently performing a routine startup check to prepare for heating your home, and this is completely normal behavior.
Your boiler is currently performing a standard internal check by running its internal fan to clear out the combustion chamber before it starts heating.
Your boiler is currently trying to light its internal flame but is waiting for the process to start.
Your boiler is currently running a standard self-check or moving water through the system, which is a normal part of its operation.
Your boiler is simply cooling itself down by running the internal fan for a few moments after it has finished heating, which is a normal part of the shutdown process.
Your boiler is currently running its internal pump to move residual heat out of the system, which is a normal part of the cooling-down process before it switches off.
Your boiler is currently performing a standard safety check, meaning it is clearing out the combustion chamber before it tries to ignite.
Your boiler is currently performing a routine check of its water circulation system and is operating normally.
Your boiler is currently trying to light its flame as part of its normal startup process.
Your boiler is currently performing a standard safety check or preparing to heat your home, and this message is simply confirming that its internal circulation systems are active.
Your boiler is simply finishing its cooling cycle to move leftover heat away from the inside of the unit, which is a normal part of the shutdown process after the heating or hot water has been running.
Your boiler is undergoing a standard cooling cycle to move leftover heat away from the system, and this is a normal part of its operation.
Your boiler is currently having a short rest period to prevent it from switching on and off too frequently, which is a normal protective feature.
Your boiler has temporarily stopped itself because it sensed an irregularity in how the internal fan is spinning, so it is currently waiting for a safety period to end before it tries to start again.
Your boiler is currently in standby mode because it is not receiving a signal from your thermostat or programmer to turn on the heating.
Your boiler has detected that the water pressure inside the system is currently too high, which may cause a safety valve to leak or prevent the boiler from running correctly.
Your boiler has detected an issue with an external add-on or a water drainage pump, which is preventing it from firing up to keep you safe.
Your boiler has detected that the water pressure inside the system has risen too high, which could cause a safety relief valve to leak.
Your boiler has temporarily stopped working because it cannot move water around your heating system fast enough, likely due to low pressure or a blockage.
Your boiler is temporarily paused because it detected low water pressure to prevent potential damage to the internal pump.
Your boiler is currently running a brief self-test on its internal water temperature sensors and has temporarily paused heating and hot water to complete this check.
Your boiler is currently running a brief automatic safety check to confirm its internal water levels before it allows your heating or hot water to start.
Your boiler is currently running a brief self-check to ensure its internal temperatures are balanced, so it has temporarily paused your heating or hot water.
Not faults — these are normal operating states. Tap to expand.
BoilerFaultCodes