High Lockout
E117 on Potterton Promax HE

Your boiler has shut down because there is too much water pressure in the system, which could lead to leaks if not addressed.

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

System pressure too high (>2.9 bar)

What causes this fault?

This fault occurs when the water pressure inside your heating system rises above a safe operating level, triggering a safety shutdown. The most common reasons are that the filling loop was left slightly open after topping up the system, or an internal component like the expansion vessel has failed and can no longer manage the pressure changes as the water heats up.

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

E118View →

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