High Lockout
AL52 on Vokera Unica 24HE

Your boiler's internal computer has encountered a memory or software error and can no longer control the heating properly.

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

What causes this fault?

This fault occurs when the boiler's control center suffers a critical failure in its internal memory or software processing. It is essentially a terminal logic error where the circuit board can no longer safely calculate how much gas or heat to provide. The most common reason is age-related degradation of the electronic components, which causes them to lose their pre-programmed settings.

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

AL55View →

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