21 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 |
|---|---|---|
| 41-288-11 | Avanta Plus 18S | 2008–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 temporarily paused because the water inside has become slightly hotter than it is supposed to be.
Your boiler has temporarily stopped working because a safety device wired into the system, such as a room thermostat or external timer, is signaling that something needs attention.
Your boiler has temporarily paused heating because the radiators are already as hot as the temperature you asked for, but it will automatically turn back on in a few minutes once it cools slightly.
Your boiler has temporarily stopped because it detected that the water inside is getting hotter than the temperature you have set, likely due to poor circulation.
Your boiler has switched itself off because the water inside is heating up too quickly or too unevenly, which often happens when water cannot circulate through your radiators properly.
Your boiler is perfectly healthy and is simply waiting for a signal from your thermostat to turn on the heating or hot water.
Your boiler has tried to start up but cannot light the gas to create a flame.
Your boiler is currently going through its safety check phase before it attempts to light, which is a normal part of the startup process.
Your boiler has failed to light the flame needed to produce heat or hot water.
This code is not actually an error; it simply indicates that your boiler is currently running to provide heating for your radiators.
Your boiler has tried to light itself several times but has failed, likely because there is no gas supply or the ignition part is dirty or broken.
Your boiler is currently in a mandatory waiting period, meaning it is simply resting before it tries to restart itself.
Your boiler is currently running its internal water circulation pump longer than expected after finishing a heating or hot water cycle, but this is usually just a system status notification rather than a breakdown.
Your boiler has detected that there is not enough water inside the system to operate safely, or the internal pump is struggling to move the water around.
Your boiler has detected that the internal fan responsible for venting exhaust gases safely is either not spinning or communicating properly, so it has shut down to keep your home safe.
Your boiler is simply running a standard three-minute safety and air-clearing cycle after a previous minor error before it attempts to turn back on.
Your boiler has detected that hot combustion gases are leaking into the internal casing, which is a serious safety concern that prevents the appliance from operating correctly.
Your boiler has recently experienced an error and is currently running a harmless three-minute safety venting cycle to clear any trapped air before attempting to restart.
Your boiler has detected that some of its internal settings have drifted outside of their safe operating limits, and it has stopped working as a precaution.
Your boiler has detected an internal software or settings error, which is preventing the system from starting up safely.
Your boiler has lost its programmed settings and needs to be reconfigured by a professional to operate correctly.
Not faults — these are normal operating states. Tap to expand.
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