High Lockout
L9 on Ideal Logic Combi ESP1

Your boiler’s main computer chip has forgotten its settings or has developed an internal electrical failure, meaning the unit cannot function.

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

PCB UNCONFIGURED OR FAULTY

What causes this fault?

This fault occurs when the boiler's main control board loses its identity or suffers an internal electrical memory failure. Essentially, the 'brain' of the unit has either corrupted its software settings or the physical circuitry has worn out, preventing it from safely controlling the 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

L1View →L2View →F2View →

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