Your boiler is performing a routine self-cleaning and safety check to fill up its internal condensate trap.
This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.
Technical description: Trap filling programme Enabled
What causes this fault?
This code appears when the boiler automatically enters a low-power mode to prime its internal drainage system with water. It is a built-in safety sequence designed to ensure the condensate trap is full, preventing harmful flue gases from escaping into your living space. The boiler will typically resume normal operation once it has finished this protective cycle.
DIY fix possible
Wait for approximately 10 to 20 minutes for the programme to finish automatically.Do not turn the boiler off during this process.The boiler will return to normal operation and show its usual temperature display once complete.
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