High Lockout
H n on Ideal Classic FF

Your boiler has detected that the electrical wiring coming into the unit is swapped or incorrectly connected, preventing it from starting 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

PHASE REVERSAL

What causes this fault?

This fault occurs when the live and neutral electrical wires leading into the boiler have been accidentally swapped, usually following electrical work in the home or a smart thermostat installation. The boiler's safety sensors detect that electricity is flowing in the wrong direction and prevent the unit from firing to avoid damage or electric shocks. In rarer cases, a fault within the internal control board can cause it to misinterpret correct wiring as a reversal.

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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