36 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 |
|---|---|---|
| 41-694-35 | ecoFIT sustain 430 VU 306/6-3 OV (H-GB) | 2018–present |
Appliance names and production years are taken from the UK Product Characteristics Database (the SAP/SEDBUK register). Where a GC number is also printed in this model's own manufacturer manual, both sources were checked to agree.
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Your boiler's display screen has lost its connection to the main computer inside, meaning it cannot control or run your heating system.
Your boiler has lost its connection to the temperature sensor, meaning it no longer knows how hot the water is and has stopped working to keep you safe.
Your boiler has lost the connection to the sensor that monitors the temperature of the water returning to the unit, causing it to stop working for safety reasons.
Your boiler has stopped working because a sensor that measures water temperature is providing an incorrect signal, so the system has safely shut down to prevent overheating.
Your boiler has detected a faulty signal from a heat sensor, causing it to shut down for safety to prevent overheating.
Your boiler has temporarily stopped working because it has detected a faulty reading from its internal temperature sensor.
Your boiler has automatically shut down because the internal water pressure has dropped too low to operate safely.
Your boiler has shut itself down because the water inside is getting too hot too quickly, usually due to a blockage or a stuck valve.
Your boiler is temporarily shutting down because the water inside is heating up much faster than normal, usually due to poor water flow.
Your boiler has temporarily shut itself down because the exhaust gas coming out of the flue is getting dangerously hot.
Your boiler has temporarily locked out because it is sensing a flame inside when it shouldn't be burning gas.
Your boiler is trying to start but cannot get the flame to light or stay lit.
Your boiler was working but has suddenly turned off because the flame has gone out and it cannot manage to relight itself.
Your boiler has detected that the internal fan responsible for safely venting exhaust gases is not spinning, so it has shut down to prevent unsafe operation.
Your boiler is having trouble communicating with its external controllers or thermostats, preventing it from receiving instructions to heat your home.
Your boiler has detected an internal electrical issue with the valve that controls the flow of gas.
Your boiler has detected an issue with the internal gas valve failing to shut off properly, which stops the appliance for safety.
Your boiler's internal computer has encountered a memory error and cannot read the essential configuration data required to operate safely.
Your boiler's internal computer has detected an electrical error, likely caused by a faulty sensor or a loose connection that is preventing it from operating safely.
Your boiler has detected that the temperature of its internal electronic components is too high, so it has safely shut down to prevent permanent damage.
Your boiler has detected an internal communication problem with its electronic control system, meaning it cannot safely confirm the flame is burning correctly.
Your boiler is temporarily locking out because the flame inside is flickering or going out unexpectedly, meaning you currently have no heating or hot water.
Your boiler's internal computer has forgotten its identity settings, preventing it from starting up correctly.
Your boiler is temporarily shutting down because it cannot accurately read the temperature of the water flowing through the system.
Your boiler has temporarily stopped working because it is getting conflicting temperature readings from its internal water pipes.
Your boiler's sensor is having trouble reading the internal water pressure, which means it has safely shut down to prevent damage until the issue is resolved.
Your boiler has detected that the water pressure inside the system is currently too high.
Your boiler has stopped working because the water pressure inside the system has dropped too low.
Your boiler has automatically shut down because a safety device detected that the main part of the boiler has become dangerously hot.
Your boiler has detected an issue with the system that removes waste water or controls the exhaust gases, causing it to lock out for safety.
Your boiler has detected that the water inside is not heating up or moving properly right after it turns on.
Your boiler's temperature sensors have been attached to the wrong pipes during installation, meaning it cannot properly measure how water flows through the system.
Your boiler has lost its electrical connection to the part that creates the ignition spark, meaning it cannot safely light to provide heating or hot water.
Your boiler has lost its electrical connection to the gas valve, meaning it cannot safely let gas through to heat your home.
Your boiler has detected an issue with the internal water pump's connection or electronic signals, causing it to shut down for safety.
Your boiler's internal computer has failed a self-test and is no longer able to communicate with the rest of the system.
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BoilerFaultCodes