High
A7 on Worcester Bosch Greenstar 35 CDi

Your boiler is currently unable to sense the temperature of your hot water, so it has shut down the hot water system to prevent it from 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

Hot water NTC sensor defective. Check hot water NTC sensor and connecting lead for circuit breaks/short circuits.

From this model's manual
Verified against the Worcester Bosch Greenstar 35 Cdi installation & service manual, page 56.
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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