59 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
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Your boiler is most likely asking for its routine annual service, which is a reminder rather than a breakdown, so it should keep working while you arrange a visit from a Gas Safe engineer.
Your boiler has lost contact with the temperature sensor on the solar panels on your roof, so it cannot tell how hot they are, but your central heating and hot water should still work normally.
Your boiler's solar hot water add-on has lost contact with one of its temperature sensors, so the solar part of the system can't read its temperature correctly, but your boiler should still heat your home and provide hot water.
The boiler has lost contact with the sensor that measures the hot water cylinder's temperature, so it cannot control hot water heating properly, though the central heating will usually still work.
Your boiler's solar heating add-on has reported a fault, but the boiler itself can usually still heat your home and provide hot water as normal, so this needs a qualified engineer to check when convenient rather than urgently.
The boiler has lost track of the outdoor temperature, so it is guessing it is freezing outside and may heat your home more than needed, but it is still working and an engineer can fix it.
The boiler has lost track of the outside weather, so it is heating your home as if it were a freezing day, which may make it run warmer and longer than needed but is not dangerous.
Your boiler has lost the sensor that measures the temperature of the water leaving it, so it is using a backup method to control the heating, and a qualified engineer should check it soon.
The boiler has lost its reading of how hot the water leaving it is, so it is using a backup method to control the heating, which usually keeps things working but should be checked by an engineer soon.
Your boiler has shut itself down because a temperature sensor that tells it how hot the water is has failed, so it cannot safely light, which means your heating and hot water may not be working until a qualified engineer repairs it.
Your boiler has shut itself down for safety because its burner has stopped working properly, and a wiring fault in one of its temperature sensors is likely the cause, so a qualified engineer should check it.
Your boiler has detected a faulty temperature reading for the heating circuit that feeds one set of radiators or underfloor pipes, so it has partly closed that circuit's valve as a precaution and that part of your home may be heating less effectively.
The boiler has lost the signal from a sensor that monitors the water temperature for one of your heating zones, so that zone's mixing valve has shut off and the zone may not be heating properly.
Your boiler has stopped heating your hot water because it has lost track of the water temperature in your cylinder, and a qualified engineer will need to replace the faulty sensor so hot water can return.
Your boiler is not heating your hot water tank because it has lost the signal from the sensor that measures the tank's temperature, usually because a wire has come loose or broken, so a heating engineer will need to check and repair it.
A temperature sensor on your solar panels is reporting a faulty reading, so the solar part of your system can't work properly, but your main heating and hot water should still be working normally.
The boiler has detected a faulty temperature reading from its solar heating system, which is usually a sensor problem that does not stop your main heating or hot water from working.
Your boiler's solar hot water sensor is reporting a fault, which usually means the solar-assisted hot water top-up isn't working, but your heating and standard hot water should still be fine.
The boiler has detected that the protection that stops the hot water cylinder from slowly corroding is not working, but your heating and hot water may still be running normally.
Your boiler's control settings have reverted to their original factory state, which usually means its controller needs to be checked or replaced by an engineer before normal heating and hot water can be restored.
Your boiler has shut itself down as a safety precaution because a sensor in the flue is sending faulty readings, so it needs a qualified engineer to check it before it can safely heat your home and water again.
The boiler's control panel has lost proper communication with its internal settings, so it may not be running as intended, but this is usually fixable by a qualified engineer.
Your boiler is still running, but its internal controls are working as if it is much colder outside than it really is, so it may heat your home less efficiently and less accurately than normal.
Your boiler's control system has reverted to its factory settings or has lost its stored configuration, so it has stopped working properly and needs an engineer to check and restore it.
Your boiler's control system cannot find or read its settings card correctly, so it may stop heating or hot water until a qualified engineer checks it.
Your boiler has switched itself off as a precaution because a wire connected to a sensor that monitors its exhaust heat has become disconnected, so your heating and possibly your hot water will not work until a qualified engineer reconnects or replaces it.
Your boiler has lost communication with the controller for one of your heating zones, so that zone may not heat properly, though the rest of your system should still work.
Your boiler is still heating your home, but it has lost its connection to the wall thermostat, so it can't adjust the temperature based on the room conditions you've set.
The boiler has lost contact with the room thermostat for one of its heating zones, so it may be heating that zone on a basic backup schedule instead of following your settings, but your home should still be heated.
Your boiler's room controller appears to be set up incorrectly, so the boiler may not be responding to the heating schedule or temperature you expect, but this is usually a settings issue that can be corrected.
The boiler's control system is having trouble talking to one of its internal communication parts, which usually needs a qualified engineer to check and correct.
Your boiler has lost contact with the solar panel controller, so it can't use the sun to help heat your water, but your heating and hot water should still work normally.
Your boiler has lost its connection to its optional remote-monitoring device, so it can't report its status online, but it will usually keep heating and supplying hot water as normal.
Your boiler's main controls have lost contact with an add-on part that helps run your heating, so it may not be working as it should, but this is usually fixable and is not a gas safety emergency.
The boiler's control unit has lost contact with a small communication part that links it to other system controls, so it may not respond properly to thermostat or remote settings.
Your boiler has lost the signal from its room thermostat sensor, so it is heating your home using only the outside temperature, which means it may not hold the room at exactly the temperature you set, but it should still keep heating and hot water working.
The boiler has lost its room thermostat reading for one heating zone, so it is controlling the heating by outdoor temperature instead, which usually keeps your home warm but may not match the room temperature exactly.
Your boiler has lost the signal from the room thermostat sensor, so it is heating your home using only the outdoor temperature readings, which means your heating may not respond precisely to the temperature inside your rooms.
Your boiler is still producing heat, but it can't read the temperature from the room sensor for one of your heating circuits, so it is running on a less precise backup setting and may not hold your rooms at exactly the temperature you choose.
Your boiler has shut itself down because its burner has become blocked or has an internal fault, so it's stopped producing heat and hot water until it's checked.
Your boiler has shut down because its burner has become blocked or has an internal fault, so it can't safely produce heat or hot water until a qualified engineer clears it.
The boiler has stopped because it cannot reliably detect the gas flame, so it has shut itself down as a safety precaution and will likely need a qualified engineer to check it.
The boiler has shut itself down because its flame sensor isn't reading the flame correctly during its startup check, so it needs a qualified engineer to look at it.
Your boiler has shut itself down because it couldn't confirm that the gas flame was lit and stable during its startup check, so it has stopped heating and hot water until a Gas Safe engineer looks at it.
Your boiler has detected a problem with how it sets up its gas burning controls, so it may have stopped or be running less well, and a registered engineer should check it.
The boiler's flame sensor isn't reading the flame correctly during its startup check, so it has stopped to stay safe, and a qualified engineer will need to check the flame sensing and burner.
The boiler has shut itself down because its burner has detected an internal fault, so it isn't producing heat or hot water until a qualified engineer checks it.
Your boiler has stopped because its burner is blocked or has an internal fault, so it has shut itself down as a safety measure and needs a qualified engineer to check it.
Your boiler has shut itself down because the hot exhaust gases leaving through the flue are running hotter than they should, which is a safety protection working as intended, so please don't keep pressing reset and arrange a check by a Gas Safe engineer.
Your boiler has shut itself down because it got too hot as a safety precaution, and it will need a reset once the cause is checked.
Your boiler has detected a flame when it should not be burning, so it has stopped as a safety precaution and needs a qualified engineer to check the gas controls before it is used again.
Your boiler tried to start but could not light its burner, so it has stopped and is not producing heat or hot water until a qualified engineer checks it.
The boiler has shut itself down as a safety precaution because its gas supply is not switching off properly when it should, so a Gas Safe engineer needs to check it before it is used again.
The boiler's exhaust fan is not starting up properly, so it has stopped itself as a safety precaution and will need a qualified engineer to check it.
Your boiler has stopped the burner safely because a part that drives the air fan has not fully shut down, so it needs a qualified engineer to check it before it will heat your home and water again.
Your boiler has shut itself down for safety because its gas burner isn't running correctly, which may be caused by a gas supply control fault or a blocked flue, so please don't keep resetting it and arrange for a Gas Safe engineer to check it.
Your boiler has shut itself down because its burner isn't working properly, so it isn't producing heat or hot water, and a qualified engineer will need to find out why.
Your boiler has stopped itself as a safety precaution, most likely because the burner is blocked or because nearby electrical interference or a control board fault is confusing its controls.
Your boiler has shut itself down as a safety precaution because its burner is blocked or it has detected an internal fault, so it may not be providing heating or hot water until it is reset and checked.
BoilerFaultCodes