High Lockout
F03 on Intergas Rapid 25

Your boiler has stopped working because its internal temperature sensor cannot send information to the main control board.

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

S1 sensor open circuit

What causes this fault?

This fault occurs when the boiler's main control board loses its electrical connection with the primary temperature sensor. This is usually caused by the internal sensor failing completely or a loose connection in the wiring harness that prevents data from being transmitted. Without this temperature reading, the boiler shuts down as a safety precaution 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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Related fault codes

F01View →F02View →F05View →

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