High
2 / U on Ideal Maximiser SE

Your boiler has detected that the water leaving the heater is much hotter than the water returning to it, meaning the system cannot circulate heat properly.

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

Temperature difference between the supply sensor and return sensor too large.

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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