Emergency
Red LED illuminated on Potterton Kingfisher MF RSL/CFL

Your boiler has automatically shut down for safety because it has become dangerously too hot, or because the flue is blocked and exhaust gases cannot escape properly.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Act immediately

Turn off your boiler and stop using gas appliances. Call a Gas Safe engineer now. This fault can be dangerous if ignored.

Technical description

Indicates an overheat condition has occurred or the Products Discharge Safety Device (TTB) has operated due to a flue blockage (CFL models), resulting in boiler lockout.

Engineer required

This is a emergency severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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