High
1 flash red on Main Insul 7

Your boiler has lost the ability to accurately measure the temperature of the water circulating inside it, so it has shut down as a precaution to prevent damage.

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 error (Bad connection to flow or return temperature sensor, Fault with flow or return temperature sensor(s), Low or no flow through boiler, Reverse flow through boiler)

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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