High Lockout
09 on Vokera Syntesi 25

Your boiler's electronic control board has developed a fault, meaning the internal computer can no longer communicate with the rest of the system.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description

PCB fault

What causes this fault?

This fault occurs when the boiler's internal computer experiences a critical electronic failure or a breakdown in its communication circuits. It is often caused by an electrical surge, moisture ingress reaching the control panel, or simply the natural degradation of the solder joints and components over several years of use.

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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