High
E11 on Keston Celsius 25

Your boiler has detected that its internal temperature sensors are giving conflicting readings and cannot confirm if they are measuring the correct pipes.

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

The automatic test for calibration of flow and return sensors has failed – check both flow and return sensors are located on the correct pipes and are producing the correct readings

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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