High Lockout
E11 on Viessmann Vitodens 100-W

Your boiler has stopped working because its internal computer board has detected a serious electronic error.

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

Control unit fault. Internal error.

What causes this fault?

This fault occurs when the boiler's main control board experiences a critical hardware failure or a communication error between its internal electronics. The most common reason is a component failure on the PCB itself, often caused by age, electrical surges, or moisture ingress from a small leak. It effectively means the boiler’s 'brain' can no longer safely manage the heating process, so it shuts down as a 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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