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

Your boiler is trying to run the heating even though you have turned the control knob to the off position, which usually indicates an internal electronic fault or a stuck component.

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

Light on constant (CH knob in OFF position) - likely caused by Autofrost stat mode or wet board

What causes this fault?

This fault occurs when the boiler's internal computer wrongly detects a demand for central heating even though you have turned the dial to the off position. The most common reason is an electrical short or failure within the main control board, which causes the system to run uncontrollably. In some cases, a mechanical part like the diverter valve can get stuck, sending confusing signals to the electronics.

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

FAIL POINT EView →FAIL POINT DView →

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