High
D4 341 on Worcester Bosch 26 CDi Xtra

Your boiler is overheating because the water inside it is heating up much quicker than it can be pumped away.

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

Primary flow temperature rising too fast

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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