High Lockout
ON FLASH ON on Baxi Solo

Your boiler has detected a problem with its internal temperature sensor 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

Thermistor error

What causes this fault?

This fault occurs when the boiler's internal temperature sensor, known as a thermistor, fails to send a reliable signal to the main control board. The most common reason is that the sensor has developed an electrical fault or has simply worn out over time, meaning it can no longer accurately monitor the water temperature. As a result, the boiler shuts down to prevent itself from 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

FLASH ON FLASHView →

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