22 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
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Your boiler is having trouble reading the outdoor temperature, which may cause your heating to behave unpredictably or run at the wrong temperature.
Your boiler has lost its ability to accurately measure the temperature of the water leaving the unit, usually due to a faulty sensor or a wiring issue.
Your boiler has lost signal from the pipe that monitors water returning to the unit, causing the heating to stop working for safety.
Your boiler has detected a problem with the sensor that manages your hot water, which usually means it cannot heat water safely or accurately.
Your boiler is having trouble communicating internally with its control components, meaning it cannot currently receive instructions to heat your home.
Your boiler has detected that the water pressure is either too low or too high to operate safely, or the sensor that monitors this pressure has lost its connection.
Your boiler has detected low water pressure and is now running a pre-programmed automatic cycle to clear any air bubbles from the pipes.
Your boiler has shut down because there is too much water pressure in the system, which needs to be lowered to a safe level.
Your boiler is currently running an automated process to remove trapped air from the system, which is a normal self-maintenance cycle and not a breakdown.
Your boiler is struggling to detect the flow of water through the system, which means it has safely shut down to prevent overheating.
Your boiler is struggling to accurately measure the temperature of the water returning to it, which prevents the system from heating your home correctly.
Your boiler is struggling to circulate water, either because there isn't enough water inside the system or because the internal pump has stopped working.
Your boiler has detected that it is running much hotter than it should be and has automatically shut itself down to prevent damage.
Your boiler has detected that the water inside has become dangerously hot and has shut itself down to prevent damage or overheating.
Your boiler has stopped working because the water pressure inside the system has risen too high for it to operate safely.
Your boiler has detected that the water pressure inside the heating system has dropped too low, so it is running at a reduced level to protect itself.
Your boiler's air circulation system isn't starting, which prevents the unit from firing up safely to provide heat or hot water.
Your boiler has failed to light the flame after several attempts and is currently unable to provide heating or hot water.
Your boiler is unable to safely vent exhaust gases because the internal fan is not spinning at the required speed.
Your boiler is struggling to pump water around your heating system correctly and has shut down to prevent itself from overheating.
Your boiler has detected that the water pressure is too low to operate properly and needs to be topped up.
Your boiler has too much water inside it, causing the pressure to rise to an unsafe level that has shut the system down.
Not faults — these are normal operating states. Tap to expand.
BoilerFaultCodes