High Lockout
F.63 on Vaillant ecoMAX 618

Your boiler's internal computer brain has developed a memory error and cannot 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 | Cause: Electronic fault

What causes this fault?

This fault occurs when the boiler's main control board suffers a hardware failure, specifically within its internal memory chip. It is essentially a digital communication breakdown where the boiler can no longer store or read the vital settings it needs to operate safely. The most common reason is age-related degradation of the electrical components or a sudden power surge that has corrupted the circuit board.

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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