35 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Replaced by: Centora
This boiler uses indicator light combinations
Note which lights are on, off, or flashing and at what speed. Match the combination to the cards below. Do not reset until you have noted the pattern. 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 |
|---|---|---|
| 47-980-23 | Calydra Comfort 100 | 2002–2007 |
Tap any card for details
Your boiler has stopped working because it cannot light its internal flame to heat your water.
Your boiler has failed to light the flame, so it has safely shut itself down to prevent a gas buildup.
Your boiler has sensed that it is getting dangerously hot and has shut itself down to prevent internal damage.
Your boiler is trying to ignite but cannot sense a flame, so it has safely shut down to prevent gas from escaping.
Your boiler has detected very cold temperatures and is running the water pump to prevent the pipes from freezing.
Your boiler has detected that the temperature is low enough to risk freezing and has automatically started its internal heating process to keep its pipes safe.
Your boiler has detected that hot water isn't moving around your radiators or pipes properly, causing it to stop to prevent overheating.
Your boiler has stopped because the water pressure inside the system has dropped too low to operate safely.
Your boiler has lost the ability to measure the temperature of your hot water, which means it will stop providing hot water until the faulty sensor is replaced.
Your boiler has stopped producing hot water because a sensor that measures water temperature is providing an incorrect signal.
Your boiler has lost the ability to monitor the temperature of the water being sent to your radiators, so it has shut down as a precaution to prevent overheating.
Your boiler is currently trying to relight itself because it failed to catch a flame on the previous attempt.
Your boiler is having trouble communicating with its internal controls due to a connection issue, which is preventing it from firing up.
Your boiler has detected that the internal exhaust fan is not spinning fast enough to safely clear fumes, so it has shut down to prevent a safety risk.
Your boiler is unable to safely move air and exhaust gases, so it has shut down to prevent any risk of fumes entering your home.
Your boiler is failing to detect the temperature of your hot water cylinder, which means it will likely stop providing hot water until the faulty sensor is replaced.
Your boiler has detected that a temperature sensor is not communicating correctly, which may prevent your hot water or heating from working reliably.
Your boiler has stopped working because it cannot light the internal flame or keep it burning.
Your boiler has detected that it is running too hot and has automatically shut down to prevent any internal damage.
Your boiler has detected an issue with the ignition process and has shut down as a precaution to prevent unburnt gas from building up.
Your boiler has detected that hot water isn't moving through your heating system properly, so it has shut down to prevent itself from overheating.
Your boiler has detected an issue with the air intake or exhaust system, causing it to shut down to prevent unsafe operation.
Your boiler has detected an issue with the ignition process and has shut itself down to prevent unsafe gas buildup.
Your boiler has detected that it is running much hotter than it should be and has automatically switched itself off to prevent internal damage.
Your boiler's main control panel and its internal display screen are having trouble sending information back and forth, causing the system to stop functioning properly.
Your boiler's internal computer is unable to send information to its main controller, which prevents the unit from starting correctly.
Your boiler has detected that it is getting too hot and has temporarily paused its operation to prevent damage.
Your boiler is not detecting enough water flowing through its internal heating system to operate safely.
Your boiler is struggling to detect the temperature of the water flowing into it, so it has safely shut down to prevent overheating.
Your boiler has detected a failure in the internal electronic control system, preventing it from operating safely.
Your boiler has detected an issue with the circuit board's ability to communicate with the system sensors, causing it to stop operating to ensure safety.
Your boiler has detected an issue with the air supply or exhaust gases, meaning it has safely shut down to prevent unsafe operation.
Your boiler has detected a failure in the internal electronic control board, preventing it from operating correctly.
Your boiler has detected a problem with the internal water circulation system, which is preventing it from heating your home or water safely.
Your boiler has detected a communication error between its internal electronic control systems, causing the system to stop operating.
BoilerFaultCodes