BoilerFaultCodes.com
AL55 High Lockout

Your boiler’s internal control board has lost its identity settings and needs to be reconfigured by a professional.

Call an engineer soon

Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: Jumper tag fault

What causes this fault?

This fault occurs when the boiler's main control board loses its memory regarding which specific model it is supposed to be operating. It is often caused by a sudden electrical surge or a physical failure of the small configuration 'jumper' tag plugged into the circuit board. Without these settings, the boiler shuts down as a safety precaution because it no longer knows its own power rating or component layout.

Typical repair cost £100-280 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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