High
LOCKOUT LIGHT ON CONSTANTLY on Worcester Bosch Greenstar 15sbi

Your boiler has switched itself off because it has detected an unsafe build-up of heat inside the unit.

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

FAULT POINT D. Overheat lockout. Possible causes: low water pressure, air in system, bypass missing, pump failure, sensor fault, or overheat thermostat trip.

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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