High
260 on Worcester Bosch Greenstar 12i System

Your boiler is attempting to fire up, but it cannot detect the expected increase in water temperature, causing it to shut down for safety.

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

No temperature rise after burner start

From this model's manual
Verified against the Worcester Bosch Greenstar 12i System installation & service manual, page 63.
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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