High Lockout
F05 on Intergas Rapid 25

Your boiler has stopped working because an internal temperature sensor that monitors your hot water or heating has developed an electrical fault.

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

S3 sensor short circuit

What causes this fault?

This fault occurs when the boiler's control board detects an incorrect electrical signal from the temperature sensor, indicating a short circuit. The most common reason is that the internal components of the sensor have failed due to age, or moisture has compromised the electrical connections. Without an accurate 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 →F03View →

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