High
E11 on Keston C36p

Your boiler's internal computer is struggling to confirm the temperature difference between the water leaving and returning to the unit, causing it to shut down for safety.

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.

What the manual says

Manufacturer manual

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.

From this model's manual
Verified against the Keston C36p installation & service manual, page 32.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

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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