34 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
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The GC number on your boiler's data badge identifies the exact appliance and production years, as recorded in the UK Product Characteristics Database.
| GC number | Appliance (register name) | Produced |
|---|---|---|
| 41-044-76 | ecoTEC plus 435 VU 356/6-5 OVZ (H-GB) | 2018–present |
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Your boiler has lost the ability for its main control brain to talk to the display screen, meaning it cannot receive commands or function correctly.
Your boiler has lost the signal from one of its internal temperature sensors, so it has shut down to prevent overheating.
Your boiler has lost the signal from a temperature sensor that monitors the water returning to the system, causing it to stop heating as a safety precaution.
Your boiler has detected an electrical fault in a temperature sensor, which is preventing it from safely monitoring the water heat levels and stopping it from operating.
Your boiler's temperature-monitoring system has detected a faulty signal, likely due to a loose wire or a broken sensor, preventing it from heating your home safely.
Your boiler is struggling to read the water temperature in your hot water tank due to a loose wire or a faulty sensor, so it has shut down the heating to prevent issues.
Your boiler has detected that it is running too hot and has automatically shut itself down to prevent damage.
Your boiler has detected that it is heating up much faster than it can move that heat away, which usually means the water pump is stuck or there is an air pocket trapped inside the system.
Your boiler has detected that it is overheating very quickly because water is not flowing through the system as it should.
Your boiler has detected that the exhaust gases are becoming dangerously hot, or a safety sensor connection has been disconnected, so it has shut down to prevent damage.
Your boiler has detected an issue with its flame monitoring system and has automatically shut down to ensure your safety.
Your boiler is failing to ignite because it cannot detect a flame or receive the necessary gas supply to start up.
Your boiler has failed to stay ignited, which means it has safely shut itself down because it cannot keep a steady flame.
Your boiler has detected that the internal fan responsible for moving air is not spinning at the correct speed or is being blocked, preventing the boiler from firing up safely.
Your boiler's communication system is experiencing an electrical connection issue that is preventing it from sending instructions correctly.
Your boiler has detected an electrical fault in the system that controls the gas supply, meaning it has safely shut itself down to prevent any unsafe operation.
Your boiler has detected an issue with its internal components responsible for safely stopping the gas flow, meaning it cannot shut down correctly.
Your boiler's main computer control panel has suffered a critical internal memory failure and can no longer process instructions to run your heating system.
Your boiler's computer is misreading temperature information from sensors, meaning it cannot safely control your heating or hot water.
Your boiler's main control unit is overheating, which has caused it to shut down for safety to prevent permanent damage.
Your boiler has detected an internal electronics error that prevents it from safely confirming if the flame is burning correctly, so it has shut down to protect your home.
Your boiler is struggling to keep its internal flame lit or detect it properly, which is preventing it from heating your home safely.
Your boiler’s internal computer has lost its identification settings, usually because a part was replaced without being properly programmed to match your specific system.
Your boiler is struggling to accurately measure the temperature of the water flowing through the system, causing the heating to stop as a safety precaution.
Your boiler has detected that the water temperature is not moving through the system as expected, which prevents it from working reliably.
Your boiler has detected a potential blockage or mechanical issue with the system that manages exhaust gases, which has triggered a safety shutdown to prevent harmful gases from entering your home.
Your boiler is having trouble communicating with the external controls or hot water system, which is preventing it from heating your water correctly.
Your boiler is not detecting enough water circulating inside the system to safely turn on the burner.
Your boiler is confused because internal temperature sensors are either misread or have been incorrectly fitted, preventing the system from heating your home safely.
Your boiler is confused because its temperature probes are detecting heat in the wrong places, likely due to a wiring issue or the sensors being moved.
Your boiler has detected that a safety sensor meant to prevent underfloor heating pipes from overheating is not sending a signal or is disconnected.
Your boiler has lost the internal connection needed to detect the flame, so it has safely shut down to prevent any gas buildup.
Your boiler has lost its connection to the component that controls the gas flow, meaning it cannot ignite safely to provide heating or hot water.
Your boiler is struggling to read the temperature of your hot water cylinder because there is a faulty connection or wiring issue with the sensor responsible for monitoring it.
Not faults — these are normal operating states. Tap to expand.
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BoilerFaultCodes