Emergency
359 on Worcester Bosch Greenstar Heatslave II

Your boiler has detected that the water inside the system has become dangerously hot and has shut itself off to prevent damage or scalding.

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.

What the manual says

Manufacturer manual

DHW outlet or storage tank exceeds 90°C

From this model's manual
Verified against the Worcester Bosch Greenstar Heatslave Ii installation & service manual, page 43.
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 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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