High
ED on Worcester Bosch Greenstar 12i System

Your boiler has detected that hot gases are building up inside the system while the water meant to be heating your home is staying cold, so it has safely shut down to prevent overheating.

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

CH: flue gas temperature rising but supply temperature not

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

EAView →CEView →

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