High Lockout
E 15 on Vokera Hydra

Your boiler's internal computer has encountered a serious error and can no longer control the system, meaning your heating and hot water will not work.

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

Internal fault (PCB)

What causes this fault?

This fault occurs when the boiler's internal computer, the Printed Circuit Board, suffers a critical electronic failure or a breakdown in communication with its sensors. The most common reason is general wear and tear of the electrical components, though power surges or moisture getting onto the board can also trigger this shutdown.

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

E 14View →E 16View →

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