8 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Replaced by: Energy System
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 |
|---|---|---|
| 41-019-01 | Ultracom 12hxi | 2007–present |
| 41-019-02 | Ultracom 15hxi | 2007–present |
| 41-019-03 | Ultracom 18hxi | 2007–present |
| 41-019-05 | Ultracom 30hxi | 2007–present |
| 41-019-06 | Ultracom 38hxi | 2007–present |
Tap any card for details
Your boiler's internal control board and the display panel have lost touch with each other, meaning the boiler cannot receive your commands to turn on.
Your boiler's internal thermometer has developed a fault and can no longer tell how hot the water is, causing the system to shut down for safety.
Your boiler has detected an electrical fault with the sensor that monitors the temperature of your hot water cylinder, meaning it cannot heat your water correctly.
Your boiler has detected that the internal mechanism responsible for clearing waste gases is not operating correctly, so it has safely shut down to prevent unsafe operation.
Your boiler is struggling to keep the flame lit while it is running, causing it to shut down for safety.
Your boiler has lost the signal from the sensor that monitors the temperature of the water being sent to your radiators, causing it to stop heating.
Your boiler is struggling to control the internal fuel supply, meaning it cannot safely ignite or maintain a flame to heat your home.
Your boiler has lost communication with its control system, meaning it cannot receive signals to start heating or hot water.
Not faults — these are normal operating states. Tap to expand.
BoilerFaultCodes