High Lockout
F.63 on Vaillant ecoMAX Pro 28E

Your boiler's internal computer brain has developed a memory error and can no longer process the instructions needed to run 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 error

What causes this fault?

This fault occurs when the boiler's internal memory chip becomes corrupted or fails to communicate with the rest of the control system. Over time, electrical components on the circuit board can degrade or be damaged by power surges, leading to a permanent failure in the unit's stored software code. Without these vital instructions, the boiler cannot safely manage the ignition or heating process.

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.65View →F.67View →

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