High Lockout
INDICATOR LIGHT FLASHING on Worcester Bosch 24i RSF

Your boiler has detected a problem with one of its internal temperature sensors and has stopped working as a safety precaution.

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

Sensor fault.

What causes this fault?

This fault occurs when the internal temperature sensors, which monitor how hot the water is getting, fail to send a reliable signal to the boiler's brain. The most common reason is that the sensor has physically degraded or developed a chemical build-up over time, causing it to provide inaccurate readings. In some cases, the electrical wiring connecting these sensors has become loose or damaged, leading the boiler to shut down to prevent overheating.

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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