High Lockout
UA-64 on Daikin D2CND

Your boiler's computer memory card is experiencing a communication error or has failed during an internal update, causing the system to stop working.

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

Blocking during boiler chip card (BBC) update

What causes this fault?

This fault occurs when the boiler's main control board loses its connection with the small plug-in memory chip that contains the unit's specific operating instructions. It is usually triggered by a physical hardware failure on the chip itself or a data corruption error that happens while the system is trying to update its internal software.

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

UA-65View →

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