High
E2 on Worcester Bosch Greenstar System

Your boiler's internal thermometer is not sending a proper signal, so the system has shut down its heating and hot water functions to avoid 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

Flow temperature sensor defect.

From this model's manual
Verified against the Worcester Bosch Greenstar System installation & service manual, page 40.
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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