Medium
2.0 on Worcester Bosch ZB 7 27 HE

Your boiler is currently in a manual testing mode used by engineers to check its performance rather than a standard fault, meaning it is not operating normally for your home heating.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

What the manual says

Manufacturer manual

Service function used to set operating mode (0. = Normal mode, 1. = min. rated heat output, 2. = max. rated heat output)

From this model's manual
Verified against the Worcester Bosch Greenstar 25i Zwb 7 25 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.

DIY fix possible

Locate the reset or 'service' button on your boiler control panelPress and hold the service button for several seconds until the display reverts from the number to a standard standby symbolOnce the display shows a normal status, turn on a hot water tap to ensure the boiler returns to standard operation

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