BoilerFaultCodesBaxi FLASH ON FLASH Fault Code
Also written as FLASHONFLASH — same fault.
The Baxi FLASH ON FLASH fault code means: your boiler's electronic control board has developed a fault, meaning the internal computer can no longer safely operate the heating system.. It appears on 3 Baxi models in our database.
Technical description: Printed circuit board (PCB) error
What causes the Baxi FLASH ON FLASH fault?
This fault occurs when the boiler's internal computer chips or electrical paths fail due to age, heat stress, or a sudden power surge. The most common reason is that the delicate components on the circuit board have worn out over time, causing the system to lose its ability to communicate with the rest of the boiler safely.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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A cover plan would handle faults like FLASH ON FLASH: no call-out fees, no surprise bills.
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Baxi models that show the FLASH ON FLASH fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Baxi FLASH ON FLASH fault code information on this page is sourced and cross-checked against the official Baxi service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026