25 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Replaced by: Greenstar Utility 18/25 (ERP)
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Your boiler is struggling to detect the outdoor temperature, which may cause your heating to fluctuate or run inefficiently.
Your boiler has detected that the water inside the unit is not reaching the temperature it expects or is overheating, causing it to shut down for safety.
Your boiler is struggling to detect water moving through its internal system, which is preventing it from safely heating your home.
Your boiler is struggling to detect water moving through the system, which means it has stopped heating to prevent damage to its internal components.
Your boiler has detected that water is not circulating properly around your heating system, so it has safely shut down to prevent overheating.
Your boiler is struggling to detect water movement, which means it has safely shut down to prevent itself from overheating.
Your boiler has detected that some of its internal electronic components or sensors are not communicating correctly or need a reset to function properly.
Your boiler has detected that the internal pump, which pushes heat around your home, is stuck or blocked and is unable to circulate water effectively.
Your boiler has detected that it is not receiving the correct signals from its internal safety sensors, causing it to shut down to prevent unsafe operation.
Your boiler is struggling to detect the flow of water needed to provide heating or hot water safely.
Your boiler is failing to ignite because it is not receiving a consistent supply of gas, which has caused the system to shut down for safety.
Your boiler is currently unable to read the water temperature correctly, which is preventing it from heating your home safely.
Your boiler is struggling to accurately measure the temperature of the water circulating through your heating system, which has caused it to stop working for safety reasons.
Your boiler has detected that although it is trying to light, it cannot confirm that a stable flame has been established, so it has shut itself down as a safety precaution.
Wind or air is blowing back down your boiler's chimney, which is preventing the exhaust fumes from escaping safely.
Your boiler's internal computer has encountered an error and is unable to communicate properly with the rest of the system.
Your boiler’s internal flame sensor is dirty and can no longer see the fire, causing the system to shut down for safety.
Your boiler is having trouble creating the spark or flame needed to start up because the internal ignition components are out of alignment.
Your boiler has lost its electrical supply and won't turn on, meaning it cannot provide any heating or hot water.
Your boiler is struggling to get the correct mix of air needed to burn the gas safely and efficiently.
Your boiler is experiencing a communication problem with its internal temperature sensor, causing it to shut down unexpectedly from time to time.
Your boiler has shut down because it is not burning fuel efficiently or safely, which is usually caused by a faulty internal sensor or an incorrect gas mixture.
Your boiler has detected an issue with the airflow or internal burning process and has automatically shut down to keep your home safe.
Your boiler has detected a communication error with its internal management system, preventing it from starting up correctly.
Your boiler is failing to light the burner, meaning it cannot produce heat or hot water.
Not faults — these are normal operating states. Tap to expand.
BoilerFaultCodes