High Lockout
Test 3 on Vokera Hydra

Your boiler has detected that the internal mechanism responsible for clearing exhaust gases is not operating correctly, so it has safely shut down to prevent any unsafe build-up.

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

Fan fault

What causes this fault?

This fault occurs when the boiler's control board cannot detect that the fan is spinning at the correct speed to safely clear exhaust fumes. The most common reasons are a mechanical failure of the fan motor itself or a blockage in the flue that prevents air from moving freely.

This fault is more frequent during periods of high winds, which can create back-pressure in the flue and prevent the fan from starting correctly.

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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