High Lockout
E 03 on Vokera Hydra

Your boiler's main internal computer is failing to communicate correctly, which has caused the system to stop working entirely for safety reasons.

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 main control board suffers a hardware failure and can no longer process signals from the safety sensors. It is usually caused by electrical components on the circuit board wearing out over time or being damaged by a sudden power surge. Because the 'brain' of the boiler can no longer guarantee safe operation, it shuts the system down entirely.

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 02View →E 04View →

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