High
b1 on Worcester Bosch Greenstar 35 CDi

Your boiler's computer has lost its internal configuration key, which is stopping it from knowing how to operate correctly.

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

Code plug not detected. Insert code plug correctly, test and replace if necessary.

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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Related fault codes

b2View →b3View →

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