High
Overheat Lockout on Keston Combi 30

Your boiler has switched itself off because it has reached a temperature that is too high, often caused by low water pressure or air trapped in the system.

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

1 Fill system to 1.0 bar - 2 Bleed radiators - 3 Check radiator valves open - 4 Reset boiler - 5 Contact Installer

From this model's manual
Verified against the Keston Combi 30 installation & service manual, page 17.
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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Related fault codes

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