54 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 |
|---|---|---|
| 41-364-14 | UNICA MAX 30S | 2021–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 has stopped working because it tried to start up several times but failed to detect a safe flame.
Your boiler has stopped working because it failed to ignite, meaning you currently have no heating or hot water.
Your boiler has detected a false flame signal inside and has temporarily paused operation to keep you safe.
Your boiler has detected a flame inside when it shouldn't be burning, so it has safely shut itself down.
Your boiler has automatically shut down because it has detected dangerously high internal water temperatures.
Your boiler has temporarily shut down because the internal safety limit thermostat detected that the water inside reached an excessively high temperature.
Your boiler is failing to light the flame or keep it running, which means it cannot provide you with heating or hot water.
Your boiler has failed to detect a flame safely and has locked itself out to prevent gas from building up.
Your boiler is failing to detect a flame, which means it cannot safely light or keep itself running.
Your boiler has failed to ignite or stay lit because it cannot properly detect the burner flame.
Your boiler is failing to detect a flame, meaning it cannot safely ignite or maintain its burner to provide you with heating or hot water.
Your boiler has failed to ignite or stay lit because it cannot properly detect the burner flame.
Your boiler is failing to detect the flame after ignition, which means it has safely shut down to prevent gas from building up.
Your boiler has failed to detect a flame after trying to light, causing it to lock out for safety.
Your boiler has safely shut down because the internal fan is failing to extract combustion gases properly.
Your boiler has stopped working because it cannot detect that the internal fan, which safely pushes harmful gases outside, is operating correctly.
Your boiler has detected that the water pressure inside the system has dropped too low for it to operate safely.
Your boiler has detected that the water pressure inside the system is too low to run safely and efficiently.
Your boiler has detected that the water pressure inside the central heating system is too low.
Your boiler has detected that the water pressure inside the system is too low to operate safely and efficiently.
Your boiler has detected a final fault with its water pressure or flow sensor, which stops it from operating safely.
Your boiler is temporarily unable to accurately measure the water pressure inside the system.
Your boiler has detected an issue with its incoming electrical power supply, which is often caused by a voltage surge or a fault on the main circuit board.
Your boiler has detected a problem with the electricity supply entering the system, causing it to lock out for safety.
Your boiler is experiencing a temporary communication error with its internal settings, which usually clears on its own after a reset.
Your boiler has a configuration error where its internal settings have been lost or corrupted, meaning it cannot operate safely until it is reset.
Your boiler has detected an electrical issue with the part that controls how much gas is burned, causing the system to shut down for safety.
Your boiler has detected an issue with how it regulates its internal gas and power levels, so it has safely paused to prevent damage.
Your boiler is failing to detect the flame correctly, so it has shut down as a safety precaution to prevent unburnt gas from being released.
Your boiler has failed to detect a proper flame when trying to ignite, leading to a lockout for safety reasons.
Your boiler has detected an abnormal temperature difference or issue with the water flow sensors, causing it to shut down for safety.
Your boiler has detected a temperature difference or communication problem between the sensors monitoring the flow and return pipes.
Your boiler has temporarily lost communication with the main heating zone sensor, meaning it may not properly regulate the temperature in your home.
Your boiler is temporarily showing an issue with the temperature sensor on the main heating zone, which may stop your radiators from working properly.
Your boiler has detected a temperature problem between its flow and return water pipes, causing it to temporarily lock out for safety.
Your boiler has detected an abnormal temperature difference between the water leaving the boiler and the water returning, or an overheating sensor on the return pipe.
Your boiler has detected an unsafe level of carbon monoxide or improper combustion, which means it has shut down to protect your safety.
Your boiler has detected a dangerous combustion issue where harmful carbon monoxide levels may be too high, so it has safely shut down to protect your home.
Your boiler has detected a blockage in the flue pipe that is preventing waste gases from safely exiting your home.
Your boiler has detected a potential blockage in the flue system, meaning it cannot safely remove combustion gases outside.
Your boiler is failing to detect a flame and has safely shut down to prevent gas from building up.
Your boiler has failed to detect a proper flame, so it has safely locked itself out to prevent gas from building up.
Your boiler has temporarily or finally locked out because it has detected a problem with the temperature sensor on the exhaust flue.
Your boiler has detected an issue with the temperature of the exhaust gases, so it has safely shut down to prevent any risk of overheating.
Your boiler has detected that its main heating component requires cleaning and has temporarily paused operation as a precaution.
Your boiler has detected a build-up of residue or soot inside the main heating component, meaning it needs a professional internal clean to run efficiently.
Your boiler has detected an unsafe level of carbon monoxide or improper combustion, which means it has shut down to protect your safety.
Your boiler has detected an issue with how the fuel is burning, which means it has safely shut down to prevent the risk of harmful gases escaping.
Your boiler has detected an unsafe level of carbon monoxide or improper combustion, which means it has shut down to protect your safety.
Your boiler has detected potentially dangerous combustion fumes and has shut itself down to keep you safe from harmful gases.
Your boiler is failing to detect a flame, which means it cannot safely ignite or stay running to provide you with heat and hot water.
Your boiler has failed to safely detect the burner flame, so it has locked out to prevent any unburnt gas from entering.
Your boiler has completely locked itself out for safety after too many failed attempts to start, and you will need a Gas Safe engineer to clear the blockage and reset it.
Your boiler has locked itself out because it tried and failed to restart too many times after encountering a previous problem.
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BoilerFaultCodes