High
348 EE on Worcester Bosch Greenstar CDi Compact

Your boiler has detected that the water inside the system is getting much hotter than it should be, so it has shut down to prevent damage or 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.

What the manual says

Manufacturer manual

HW: supply temperature too hot

From this model's manual
Verified against the Worcester Bosch Greenstar Cdi Compact installation & service manual.
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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