High Lockout
E12 on Remeha Avanta Plus 35c

Your boiler's computer brain has developed a software or hardware glitch and can no longer communicate with the rest of the system.

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 control unit error

What causes this fault?

This fault occurs when the boiler's main control board suffers an internal electronic failure or a software crash that prevents it from managing the heating process. It is often caused by aging electrical components on the circuit board or a sudden power surge that disrupts the unit's delicate memory. In some cases, loose wiring connections between the display screen and the main board can also trigger this communication breakdown.

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

E02View →E04View →E11View →E32View →

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