82 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
The fault code is already on your display
Note it down before pressing reset — resetting clears the code immediately. How to read fault codes →
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 |
|---|---|---|
| 47-044-52 | ecoTEC pro 30 H combi A VUW GB 306/5-3 | 2015–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.
Tap any card for details
Your boiler has lost connection with its internal thermometer, meaning it cannot safely tell how hot the water is and has shut down as a precaution.
Your boiler has stopped working because it cannot communicate with the sensor that monitors the temperature of the water returning from your radiators.
Your boiler has detected an electrical fault with the internal sensor that monitors the temperature of the water leaving the unit, causing it to shut down for safety.
Your boiler has stopped working because a internal sensor that monitors the temperature of the water returning to the unit has developed an electrical fault.
Your boiler has shut itself down because it has detected that it is getting far too hot, usually due to a lack of water flow or a circulation blockage.
Your boiler has temporarily stopped working because the water pressure inside the system has dropped too low.
Your boiler has shut down because water isn't moving through the system quickly enough, causing it to overheat too rapidly.
Your boiler is shutting down because the water inside is heating up much faster than normal, which usually points to a blockage preventing proper water flow.
Your boiler has automatically shut down because the exhaust gases leaving the system are dangerously hot.
Your boiler has detected an issue with the gas valve that controls the fuel supply, meaning it cannot safely ignite.
Your boiler has detected a signal that suggests a flame is present even when the burner is turned off, causing it to shut down for your safety.
Your boiler is trying to start up and ignite the gas, but the flame is failing to light.
Your boiler tried to light its flame several times but couldn't stay lit, so it has locked itself out for safety.
Your boiler has stopped working because it cannot detect that the internal fan, which safely pushes harmful gases outside, is spinning correctly.
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 issue with the internal gas valve control, meaning it cannot safely release gas to light the burner.
Your boiler has detected an issue with the gas valve shutting down properly, meaning it is safely locking itself out to prevent any potential safety hazards.
Your boiler's internal computer has encountered a memory error and cannot read the essential configuration data required to operate safely.
Your boiler has detected an internal electronic or sensor glitch and has safely shut down to prevent damage.
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 computer memory has become corrupted, usually after a part has been replaced without being programmed correctly.
Your boiler is temporarily unable to accurately measure the temperature of the water flowing through the system, so it has safely shut down to prevent overheating.
Your boiler has detected a temperature mismatch between its internal water pipes, meaning it cannot safely regulate its heating.
Your boiler is temporarily locked out because the internal sensor is not properly reading the water pressure in the system.
Your boiler has detected an electrical fault with the internal water pressure sensor, which is sending an abnormally high signal.
Your boiler has detected a pressure drop or a problem with the water pump upon starting up, so it has safely shut down to prevent damage.
Your boiler has detected an issue with the way waste water or gases are leaving the system, causing it to lock out for safety.
Your boiler has detected a communication issue with a hot water sensor, which temporarily affects its ability to properly regulate the temperature of your hot water.
Your boiler has detected an abnormal temperature difference between its sensors, meaning it cannot safely regulate the heat.
Your boiler has detected a confusing difference in temperature readings between its internal sensors, so it has safely shut down to prevent damage.
Your boiler has detected that its temperature sensors have been installed on the wrong pipes during recent maintenance or installation.
Your boiler is currently on standby because it has not been asked to provide any heating or hot water.
Your boiler is preparing to provide heating by turning on its internal fan, which is a normal part of its everyday startup process.
Your boiler is simply preparing to turn on the heating by getting the water circulating, which is a normal part of its startup routine.
Your boiler is simply preparing to fire up and provide central heating to your home.
Your boiler is operating normally and has successfully turned on the heating to warm up your home.
Your boiler is simply running its internal pump and fan for a brief moment after heating to cool itself down safely.
Your boiler is simply running its fan for a short moment to cool down safely after the heating has turned off.
Your boiler is operating normally and simply running the internal water pump for a short moment after heating finishes to cool itself down.
Your boiler is temporarily pausing between heating cycles to prevent the system from wearing out too quickly.
Your boiler has correctly detected that a hot water tap has been turned on and is preparing to heat the water for you.
Your boiler is simply preparing to provide hot water by starting up its internal fan, which is a normal part of its routine operation.
Your boiler is simply preparing to heat your tap water as soon as you turn a hot tap on.
Your boiler is simply letting you know that it is actively heating water for your hot taps or shower.
Your boiler is just safely cooling down after running hot water, which is a normal part of its shutdown process.
Your boiler is simply running its fan for a short time after you turn off the hot water to safely clear out any remaining heat.
Your boiler is simply running its pump for a short moment after turning off your hot water to safely cool itself down.
Your boiler has successfully detected a request for hot water and is starting up to heat your water.
Your boiler is simply preparing to provide hot water by starting up its internal fan as normal.
Your boiler is simply preparing to heat your hot water by starting up the water pump.
Your boiler is simply working normally to heat up your water when you turn on a hot tap.
Your boiler is currently operating normally to heat up your hot water for taps and showers.
Your boiler is simply running its internal pump to cool down after you have finished using the hot water taps.
Your boiler is simply running its internal fan for a short moment after you finish using hot water to safely clear out any remaining heat.
Your boiler is just safely cooling down after running the hot water tap, which is a normal part of its shutdown process.
Your boiler is temporarily delaying heating hot water to protect itself from turning on and off too frequently, which is a normal safety feature and usually resolves itself within a few minutes.
Your boiler is temporarily pausing the heating because an external room thermostat or smart control is telling it not to switch on.
Your boiler is simply set to summer mode, which means the central heating is turned off while hot water continues to work normally.
Your boiler is pausing briefly to check that the exhaust fan is ready before it safely switches on.
Your boiler has automatically activated its built-in frost protection mode because the internal temperature has dropped too low.
Your boiler has temporarily stopped because a safety device, such as a high-limit thermostat or condensate pump, has been triggered.
Your boiler is currently pausing its operation as a temporary safety measure to protect itself, and it should resume normal heating once the internal temperatures balance out.
Your boiler has stopped working because the water pressure inside the system has risen higher than it should be.
Your boiler has temporarily stopped working because it has detected an issue with the safety flap in the exhaust pipe or the water drainage pump.
Your boiler has temporarily adjusted its settings to keep working smoothly because the flame flickered slightly at a very low power setting.
Your boiler has temporarily paused heating because it detected not enough water or a blockage stopping heat from flowing away properly.
Your boiler has temporarily paused to protect itself because the water pressure inside the system has dropped too low.
Your boiler is currently taking a temporary pause as part of its built-in testing programme and should resume normal operation on its own very soon.
Your boiler is temporarily running at a lower power than usual to protect itself or manage your home's current heating needs.
Your boiler has detected a configuration mismatch between its internal computer setting and the type of gas being supplied to your home.
Your boiler is currently running a calibration routine to measure and adjust its combustion levels.
Your boiler has paused its operation because it detected a potential problem with the gas supply route to the unit.
Your boiler is reminding you that a scheduled service is due soon, while also suggesting you check the water pressure.
Your boiler is simply running its automatic air-purge routine to clear trapped air from the system, which usually happens right after it has been switched on or refilled.
Your boiler is currently running an automated safety check to test how well water is flowing through the system.
Your boiler is temporarily pausing operation to run a mandatory self-test on its exhaust gases, but this is usually an automated state that clears on its own.
Your boiler is currently running a quick diagnostic self-check on one of its internal temperature sensors.
Your boiler is currently running a brief internal check on its water pressure sensor to ensure it is reading correctly.
Your boiler is currently running a routine internal safety check to test its temperature sensors before allowing the system to operate.
Your boiler is currently running through its internal diagnostic safety test upon startup, which is a normal automated process rather than an actual fault.
Monthly cover means no unexpected bills when your boiler breaks down.
Affiliate links. We may earn a commission at no extra cost to you.
BoilerFaultCodes