High Lockout
FAIL POINT E on Worcester Bosch 24/28CDi II RSF

Your boiler is not detecting that you have turned on a hot water tap, so it isn't starting the burner to heat the water.

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

No red light (other lights function in other modes) - HW Mode

What causes this fault?

This fault occurs when the boiler fails to sense the flow of water when you open a hot water tap. It is usually caused by a rubber diaphragm that has perished or a mechanical internal switch that has become stuck, meaning the 'demand' for hot water never reaches the boiler's control board. Without this signal, the boiler remains idle because it doesn't know it needs to start the burner.

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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