High
278 F0 on Worcester Bosch Greenstar 12i System

Your boiler's computer has detected that one of its internal sensors is sending back confusing or missing information, so it has shut down as a precaution to prevent system errors.

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

Sensor test failed

From this model's manual
Verified against the Worcester Bosch Greenstar 12i System 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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