High Lockout
F.63 on Vaillant Turbomax Plus 828

Your boiler's internal computer has developed an electrical communication error and can no longer control the heating process safely.

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

EEPROM (Electrically Erasable Programmable Read-Only Memory) error

What causes this fault?

This fault occurs when the boiler's central control board suffers an internal memory failure, meaning it can no longer store or read the vital settings needed to operate safely. It is typically caused by the steady degradation of electronic components over time or a sudden electrical surge that corrupts the board's permanent memory. Because the boiler no longer knows its own configuration, it shuts down immediately as a safety precaution.

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

F.61View →F.62View →F.64View →F.67View →

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