High
347 on Worcester Bosch Greenstar 2000

Your boiler has stopped because the water returning from your radiators is hotter than the water leaving the boiler, which usually means the internal sensors are confused or the water is flowing the wrong way.

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

Return temp exceeds flow temp for over 20 sec

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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