BoilerFaultCodesPro 8 Fault Code
The Pro 8 fault code means: your boiler is currently stuck in the starting-up phase and is struggling to complete its internal safety checks.. It appears on 1 Pro model in our database.
Technical description: Displays “8” blue light on/off (Power on sequence)
DIY fix possible
Press and hold the Reset button for 5 secondsTurn the electrical power to the boiler off at the fused spur switch, wait 30 seconds, and turn it back onCheck if any other gas appliances in your home are working to ensure gas is reaching the property
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A cover plan would handle faults like 8: no call-out fees, no surprise bills.
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Pro models that show the 8 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Pro 8 fault code information on this page is sourced and cross-checked against the official Pro service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026