High Lockout
F13 on Saunier Duval Isotwin F30E

Your boiler's internal computer has lost communication with its electronic components and needs a professional reset or repair.

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

Main board connection fault. Main board defective. Check connection and wires

What causes this fault?

This fault occurs when the boiler's main control centre can no longer send or receive signals from its internal components, causing the system to freeze up for safety. The most common reason is a physical breakdown of the circuitry on the main board or a loose connection in the wiring that links the components together.

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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Related fault codes

F12View →

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