High Lockout
E167 on Potterton Promax

Your boiler's internal computer has developed a fault and can no longer control the heating or hot water 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

Printed circuit board (PCB) fault

What causes this fault?

This fault occurs when the boiler's main control board suffers an internal hardware failure or a memory error, meaning it can no longer process instructions. The most common reasons for this are electrical surges, general component wear over time, or moisture getting onto the circuitry.

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

E168View →E160View →

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