13 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 |
|---|---|---|
| 41-310-32 | iR15 | 2015–present |
| 41-310-34 | iR18 | 2015–present |
| 41-310-36 | iR24 | 2015–present |
| 41-310-38 | iR32 | 2015–present |
| 41-310-40 | iR40 | 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.
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Your boiler is having trouble reading the temperature outside, which helps it decide how hard it needs to work to heat your home.
Your boiler has stopped heating because it is unable to accurately measure the temperature of the water leaving the unit.
Your boiler has detected an issue with the sensor that monitors water returning from your radiators, causing the system to stop running for safety.
Your boiler has lost connection with the sensor that monitors your hot water temperature, meaning it cannot heat your water safely.
Your boiler has lost its internal connection to the main control board, meaning it cannot receive the commands needed to fire up and heat your home.
Your boiler is currently running an automatic air-purging sequence to clear air from the system following a power cut or being switched back on.
Your boiler has shut down because it detected it was getting too hot or a temperature sensor has failed.
Your boiler has reached an unsafe temperature and shut down to prevent damage or overheating.
Your boiler has stopped working because an internal safety electrical connection is missing or has come loose.
Your boiler has stopped working because the fan that clears exhaust gases is not spinning, preventing the system from starting up safely.
Your boiler is failing to light the gas to create a flame, meaning you will not have any heating or hot water until it is reset or repaired.
Your boiler has stopped working because the internal fan, which safely exhausts fumes, isn't spinning at the correct speed.
Your boiler has detected that water is heating up too quickly or moving in the wrong direction, which usually means the water isn't circulating properly through your radiators.
Not faults — these are normal operating states. Tap to expand.
BoilerFaultCodes