High Lockout
0E34 on Alpha Pro Tec Plus

Your boiler is struggling because the electricity supply it is receiving is weaker than it should be.

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

DHW sensor out of range (measures a temperature outside normal working range.)

What causes this fault?

This fault occurs when the sensor responsible for monitoring your hot water temperature sends an impossible reading to the boiler's internal computer. It is usually caused by the sensor failing internally due to age or a loose connection in the wiring that prevents the signal from reaching the control board.

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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